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Volvo 7 Series Guide

Electrical: Engine Starting, Charging
file:///C|/Users/Steve/Documents/Volvo%20FAQ%20Updated/ElectricalStarting.html[01/13/14 10:02:47 PM]
Electrical: Engine Starting, Charging
FAQ Home
Volvo Maintenance FAQ for 7xx/9xx/90 Cars
Jump-Starting Engine Procedures
Jump Starting Alternator Procedures
Alternator & Starter Applications & Parts
Starter:
Starter and Solenoid Problems
Starter Will Not Engage: Start Inhibitor Switch
Removing Starter
Diesel Starter Fails: Wiring Fault
Alternator and Charging:
Alternator Mounting Bushings
Alternator Not Charging
Alternator Getting Weak; Regulator/Brush
Replacement
Checking Alternator Diodes
Testing Alternator/Battery Voltage
Alternator Wiring is Failing
Alternator Interchange
Battery, Terminals, and Wiring:
Slow Battery Discharge
Starting Problems and Battery Cable/Terminal
Corrosion
Unexplained Drivability Problems; Rotting Battery
Wiring Harness; Loose Connector Nut
Car Battery Failure: Diagnostics
Car Battery Replacement Tips
Battery Explosion; Wiring Chafing
Electrical: Engine Starting, Charging
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Jump-Starting Procedures. When jump-starting a car with a dead battery, the
proper procedures to ensure personal safety and car reliability are:
1. Ensure that the cars are not touching to prevent unwanted ground/earth
paths. Do not allow the cable clamps to touch each other.
2. Put out cigarettes before opening the hoods. Wear safety glasses in case a
battery explodes (more common than you would think!)
3. Turn both cars' ignitions "off".
4. Connect one end of red wire to positive (+) bad car battery terminal
5. Connect other end of red wire to positive (+) good car battery terminal
6. Connect one end of black wire to negative (-) good car battery terminal
7. Make last connection with other end of black wire to bad car engine ground
point (such as a lift metal hook) away from the battery. This eliminates
sparking near the bad battery, which may be outgassing hydrogen and could
explode. Do not attach the cable to the negative terminal of the dead
battery.
8. Start good car engine. Stand away from the batteries.
9. Start bad car engine
10. Turn on both car headlights (see below)
11. Disconnect in inverse order, being careful to keep cables and clamps from
touching.
[Tip from Paul] The book "Bosch Fuel Injection Systems" by Charles Probst notes
that after the jump and before cable removal one should put a load on the car by
turning on headlights or the rear window heater. A lightly loaded car may
experience a spike AFTER you remove the jumper cables since the regulator was
set to supply a heavy load. You instantly switched from a heavy to light load and
the voltage may spike. You may damage your fuel injection computer with this
spike. Avoid it by engaging a load.
Note: You can print these instructions out, xerox onto a plastic sheet, and mount it
near your car battery for on-site reference.
Electrical: Engine Starting, Charging
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Alternator Stops Charging: How to Get Home? My battery charging light just
came on and I am far from home. Belt is fine. What to do? [Steve] No reason to
be stranded because of this problem. You can get it home like this: Simply run a
hot wire from the battery positive and connect it to the terminal on the back of the
alternator....the one with the small red wire connected to it. This wire provides
excitation voltage for the alternator. If you can get the engine started and then
apply 12 volts to the excitation terminal, the alternator will charge. You don't even
have to connect the wire. Simply touching the jumper wire to the terminal will
cause the alternator to start charging, and remain so as long as the engine is
running. If you did connect it, you will need to disconnect it when you stop the
engine else it will drain your battery.
Alternator & Starter Applications and Parts. [Dave Stevens] Wood Auto
Supplies Ltd. in the Huddersfield, Yorkshire, UK has an excellent on-line alternator
and starter reference tool for parts. Visit http://www.woodauto.com to enter their
site. They ship worldwide. For alternators/starters, if you know the Bosch (or
Marchal or whatever) part number then enter it in the upper right search box. Each
major listing will give you the specs, a list of equivalent or similar units, the Volvo
part numbers, the years, models and engines in which it was used and a list of the
component replacement part numbers and an indication of availability. Many of
those components are linked to their own page with further information on the part
including a typically long list of all the alternators/starters in which that part was
used. If you don't have the alternator/starter number handy then you can use this
vehicle search page:
http://www.woodauto.com/woodauto/vehicle.aspx. First, make sure the upper right
search box is clear (or you'll come up empty). Select Volvo as the manufacturer
and then your particular model and/or engine. You'll then be given a list of the
alternators and starts by model year and application. You may need to try a couple
of model/engine/alternator/starter configurations to find the appropriate list of
alternators/starters. From the list just start following the hotlinks to find the full
descriptions and the parts you're interested in. Most are complete with pics. [Jay
Simkin] Contact Barsanco in Centerline, Michigan (800-421-3374) for starter and
alternator parts (diodes, etc.) to rebuild your own units.
Starter:
Starter and Solenoid Problems.
What causes a starter to fail?
[Tips from Counterman Magazine, August 01 & Underhood Service, May 04] Starter
problems can be caused by worn brushes (carbon pads inside the motor that
supply current to the rotating armature), by shorts or opens in the armature or
field coils or by worn bushings that increase drag or allow the armature shaft to
rub against the pole shoes. Continuous and prolonged cranking is very hard on a
starter because it generates excessive heat. If not allowed to cool down every 30
seconds or so for at least a couple of minutes, the starter will be damaged by
continuous cranking. Other failure modes include:
Electrical: Engine Starting, Charging
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"Zero engagement" or "no-clicking" activation of the starter solenoid. This can
be caused by an unintentional activation of a vehicle anti-theft system. In
other cases, a defective ignition switch, start inhibitor switch, or bad wiring
harness/loose wiring connection can cause the problem. The most accurate
way to test these components is to connect a DVOM to the primary wire
connection on the starter solenoid. Using the min./max. feature found on most
professional DVOMs or multimeters, record the voltage at the solenoid terminal
when turning the ignition switch to the "crank" position. If battery voltage is
recorded, the above components should be considered in good condition. If the
starter clicks, but doesn't engage, the problem is usually caused by a faulty
starter solenoid that's not engaging the starter drive gear. In most cases,
replacing starter solenoids is not a cost-effective procedure compared to
replacing the defective starter with a remanufactured unit.
Starter motor is running but fails to engage the flywheel ring gear or when the
engagement is rough and noisy. In most of these cases, the overrun or one-
way roller clutch on the starter drive gear is worn or sticking. In the remainder
of these cases, the flywheel ring gear itself is either worn, or has broken or
missing teeth.
Low-cranking speed issue caused by worn shaft bushings. The starter's
amperage draw will be unusually high for the application. Also, when starter
current draw is high, remember that battery voltage will often drop below 9.6
volts. This is enough to affect system electronics, which, in turn, will affect
fuel pump operation. Engines must crank at about 200-300 rpm to activate
the electronic fuel injection. When the ECU "sees" a strong, sustained signal
from the crankshaft position sensor, it will activate the fuel pump relay in
order to pressurize the fuel injectors. Without a reliable RPM signal indicating
sufficient cranking speed, the ECU may not activate the fuel pump relay,
thereby creating a cranking, no-start condition.
Keep in mind that simply dropping a permanent magnet starter can fracture a
field magnet, which may cause a variety of cranking speed symptoms.
Troubleshooting the Starter
In the Shop:
To accurately test a starter, you need a test stand that can measure amp load,
voltage and rpm. A good starter will normally draw 60 to 150 amps with no load on
it and up to 250 amps under load (while cranking the engine). The no load amp
draw will vary depending on the type of starter. If the amp draw is too high, the
starter needs to be replaced. The same is true if the starter doesn't achieve the
specified rpm.
Sometimes the starter motor works fine but the drive gear won't engage the ring
gear on the flywheel. If the drive gear mechanism can be replaced separately,
there's no need to replace the entire starter. A bad solenoid can also cause starter
problems. The solenoid acts like a relay to route power directly to the starter from
the battery. It may be mounted on the starter or located elsewhere in the engine
compartment and is usually connected to the positive battery cable. Corrosion, poor
ground at the solenoid mount or poor battery cable connections will prevent the
solenoid from doing its job.
If the starter tests okay but fails to crank, another possible cause may be a bad
Electrical: Engine Starting, Charging
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ignition switch, neutral safety switch or clutch safety switch. A low battery and/or
loose or corroded battery cables can also prevent the starter from cranking the
engine.
On the Car:
When troubleshooting the starter, pay close attention to the wire/cable connections.
The starter needs a healthy shot of juice to get going so you need to clean all
contacts. Just because they appear OK when the starter is not engaged doesn't
mean that they are good enough to do the job. Check ground straps. Make sure
your fuses are clean. Check any other device on the starter circuit (if any).
Make sure your battery is OK - turn your headlights, fan, rear de-mist etc. all
on and check the voltage - should be at least 11V. If it's less than 9 or so you
may not have enough power to turn the engine over.
Test the battery terminals - should be clean and tight. If your starter won't
turn I'd remove and clean them, then coat them with some Vaseline and put
back. Also test the connection between the wires and the terminals - again,
should be tight and clean. The usual symptom of loose connections here is
that the starter solenoid 'clicks' but the engine doesn't turn.
Test the + wire (the big thick one) connection on the starter. Again, this
should be a good connection. The starter draws several hundred amps, and a
connection that's not 100% is quite likely to drop most of the battery voltage
across it.
Make sure the starter is bolted to the engine properly - the current goes
through the starter and block. Also make sure the engine is grounded - it
should have a big earthing strap, or sometimes the battery - terminal is
connected directly to the block - either way, make sure the contacts are good.
If all of the above check OK, simply put a wire from the battery + to the starter -
connect it to where the thin wire goes. This should make the engine turn over (but
not start unless the ignition is on). If the engine turns, it means that you have a
problem in the wire between the ignition switch and the starter; If it doesn't, the
starter is faulty: If you don't hear a 'click' the solenoid is to blame, otherwise the
starter motor itself.
Starter Will Not Engage: Start Inhibitor Switch.
[Symptoms: I have an 89 740GL that sometimes starts but sometimes does not.
When I turn the key the car simply will not turn over: no starter response on key
to "start". However, all of the panel lights, the battery level and starter assembly
are good. When this happens I usually put the car in Neutral and then back in Park
which usually works allowing the car to start.]
[Response:] If your car is an automatic, like my wagon, make sure that the start
inhibitor switch located under gear indication panel is not out of adjustment. A
simple test is to push the selector forward or back a little in the P position (the only
one the car should start in) as you turn the key. If the car starts, crawl under and
adjust the rod just a little and the problem should be solved once and for all.
Failing this option, check the switch and wires associated with the lockout switch.
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[Response: JohnB] Took about 250K and 16 years, but there it was: a potential
pattern failure at the start inhibitor (neutral safety) switch. A nice square contact
(should be rounded and smooth--the other one was) point due to wear and a
relaxed copper alloy arm...the car wouldn't start unless the switch was compressed
by hand (a get-home crutch, BTW!). And beware...the Volvo part comes with a new
and cheaper connector that the dealer crutches by selling you four terminals and
the late model socket for an additional $5.00!! You're supposed to clip the OEM
chassis harness clip off and crimp the new male spade terminals on and install the
late model socket so the new NSS can plug into it...I just used the old socket and
spliced it onto the new NSS. This same NSS is used on the 9xx series....
Removing Starter. The top starter bolt is difficult to remove. Before you go crazy,
see the last comment in this paragraph.
Removing Without Lowering the Transmission. You need a 1/2 inch six point 18mm
socket (940; 740 may require 19mm) or a swivelling socket, a 1/2 inch universal
joint, a large breaker bar, and enough socket extensions (with one about 36"long )
to reach back underneath the car to where you can apply the proper leverage to
get a firm grip on the bolt head. Use an impact socket if you need to. The breaker
bar should be at the rear of the transmission near the crossmember. The higher the
car, the better, but I've always done it with the car sitting at jack height. And it's
always worked. Unless you are using a lot of extensions and a universal joint, you
are going to have a hard time with this bolt. Apply some penetrating oil to the bolt
before beginning. You have to get into a position to really, really get on it!
Leverage is the key: line up the socket, the uni-joint and the extensions just right,
position yourself so you can put your weight into it, then you'll hear it: CRACK! Its
not a job for half effort. The placement near the crossmember allows you room to
use the breaker bar. While there is usually no need to remove the crossmember
and lower the rear of the transmission, if you have problems place a jack under the
tranny and remove the tranny support for better access. Do NOT drop the starter,
which may fracture an internal motor magnet. Diesel starter: see the FAQ Section.
[Art Benstein] If the above fails, use a 12 inch open end wrench from the topside
along the firewall. Apply a piece of oak 1"x1" to lever against the rear engine lift
point. You only have room to loosen 1/8 of a turn at time! [Ted Yaffo] Use an
impact wrench with requisite extensions to loosen this otherwise impossible bolt.
Removing by Lowering the Transmission.[Adam Stadnick] If you put a jack under
the transmission support crossmember, remove the four bolts holding it up, and
carefully lower the transmission down a few inches (being careful not to smash the
distributor cap if it's a head-mounted distributor) it greatly opens up the access to
the infamous upper starter bolt. I was able to remove it using 3/8" drive tools
without a breaker bar or torch or anything. I spent about an hour trying to fight
that bolt and never even got a tool to seat on it, but as soon as I lowered the
transmission it took about ten minutes start to finish.
Diesel Starter Fails: Wiring Fault.
[Inquiry:] I own a 1986 Volvo 740 Diesel. The mechanics have replaced the starter
six times from March 1999 to July 1999. The starter itself is still under warranty,
but each time I have to pay the installation labor, besides the headache of being
stranded, towing, etc. I'm not a mechanic, but even I know that something is
wrong, wrong, wrong. Does anyone have any ideas? Even a list of possibilities that
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I could have the mechanics check-out.
[Response: Van Audekerce Remi/Brandon] I have seen this quite a few times and it
was always a short in the wiring harness that engages the starter when the engine
is running. Most likely the place were the wires have rotted is where the wiring
harness runs near the diesel pump. Cut the black sleeve open and check the wiring,
most likely the wire insulation will fall apart. Check ground connections, the wiring
harness, and battery condition. With a diesel starter requiring 2 kilowatts that
comes out to 250 amps at 8.0 volts cranking. Any slight resistance will slow things
down in a hurry.
[Noel DeSouza]In my case, the grounding wire going from the battery to the
engine was bad, so check the obvious first. Use one side of a battery jumper wire
clamped so as to ground the starter body (the head of the starter-bolt is a good
spot to clamp) and the other side clamped to the negative post of the battery, then
try starting again. If it turns over, the ground wire or connections are bad.
Alternator and Charging:
Alternator Mounting Bushings. [Editor] Over time, the three rubber bushings
securing your alternator in its engine bracket can compress, allowing the pulley to
become misaligned with the crank pulley and accelerating belt noise and wear. You
can replace these with OEM rubber bushings or aftermarket polyurethane, which
are more robust and do not compress as easily. The latter may be had from IPD.
To replace your bushings:
Disconnect battery negative terminal
Use penetrant oil to loosen the tension adjusting, securing, and bracket nuts
but don't soak the belt
Unscrew the 10mm tensioner adjusting bolt beneath the side of the alternator
by about 1.5 cm. Remove the belt from the pulley.
Loosen the 12mm bottom securing nut and remove it from the adjusting
assembly
Loosen the top long bolt and nut (12 & 13mm) supporting the alternator in its
bracket
Remove the bottom nut and bolt (12 & 13mm) holding the alternator to the
bracket
Swing the alternator up. Using a screwdriver, push out the old bottom bushing
and replace it
Swing the alternator back down and replace the bottom bracket bolt and nut
Remove the top long bolt and nut and swing the alternator back to replace the
two top bushings
Replace the top bolt and nut and the securing nut
Tighten the bracket nuts (not the securing nut!) and retension the alternator
belt so you can press it down about 1/4 inch under moderate finger pressure
Once you tension it, tighten the securing nut firmly and then back off the
adjusting bolt so it bears no tension from the belt
Reconnect the battery negative terminal
If you are interested in replacing the four air conditioning compressor bushings, see
the FAQ file.
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Alternator Not Charging. When the battery loses charge and the alternator
appears not to be charging, here are some diagnostic tips:
Diagnostics. [Response: Danny Halamish] It sounds like it's probably the charging
system. Here's what I would check (in this order):
Battery terminals - clean? Good connection? Corrosion?
Alternator (thick) wires - both plus and ground (if fitted) - make sure they are
OK.
Alternator brushes - if they are nearly dead, this can cause this.
Harmonic Balancer: the alternator belt runs off the balancer. If the rubber
insert deteriorates, the balancer shell will slip
If all that checks out OK, I would suggest you get a volt meter, and when the
voltage reads a little low, measure at the alternator: It should be 14.4V. If it's
much less, rev it up a little - does the voltage go up? If not, there is a problem.
Also, with the engine running and the voltage low (i.e. when the problem happens)
measure the following:
1. Voltage between the alternator power terminal and the battery + terminal
should be well under 0.2V
2. Voltage between the alternator body and the battery "-" terminal should be
well under 0.2V
3. Voltage between the battery "-" terminal and the engine
block should be well under 02.V
Voltage Regulator. If all this checks out but you still have a
problem, the alternator voltage regulator may be defective. There
are two screws holding it into your alternator. You don't even need to pull the
alternator. Remove it and you'll probably find the two brushes (two black square
spring loaded shafts) worn out. A good electrical shop can replace these, or a new
regulato rfor either Bosch or Nippon Denso alternators is about $60. Install and,
get a boost and happy motoring.
[Testing Bosch voltage regulator on 7xx/9xx cars: How can you tell if your voltage
regulator has gone bad?. What tests can you do?
[Answer:] The real purpose behind the regulator is to keep the battery voltage
from getting too high. When my regulator went bad, voltage would increase with
engine speed, going as high as 18-20 V. You can easily test the regulator function
by using a voltmeter to test voltage between your battery and ground while the car
is running. Look for voltage between 13.8 and 14.6. If your voltage is higher than
this, you probably do have a bad regulator. Check the integrity of the regulator
diodes on a Bosch alternator by using a multimeter to measure the voltage
readings at the D+ terminal and B+ terminal. The voltage reading should be the
same at both terminals. A difference of more than one volt would indicate faulty
diodes and the need to replace the regulator unit. [Rick Ledbetter] Test the diodes
by disconnecting one of the D+ or B+ leads on the regulator and connecting your
probes: black is ground (use the alternator case for ground) and red is touched to
the D+ and B+ terminals. At the component level, diodes will only conduct one
way. They have to be tested out of circuit, so one lead has to be disconnected from
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the circuit. A simple continuity test on the meter will do the job. If you have a
failure, the Bosch regulator/brush pack unit is easy to replace with the alternator in
the car. If your battery has been overcharging, it can boil off electrolyte and may
need to be topped off.
Exciter Current Through the Warning Lamp on the Panel. The alternator
(charging) warning light in the instrument cluster feeds a small amount of electrical
current to the field coils in the alternator when you turn the key on and the engine
isn't turning. This excites the coils (electromagnet) and the alternator gets the
magnetic field it needs to start charging as soon as the engine runs. When the
alternator isn't charging at all (engine stopped) that wire to the alternator also
provides a ground path for certain warning bulbs in the cluster, so they light up.
Diodes in the network keep current from backfeeding into unwanted circuits. So if
you have a bad connection for the alternator warning wire, the alternator won't
start charging right away. But most alternators will self-excite once the revs get
high enough (say 2000 engine RPM) and then they stay excited and charging, even
at idle RPM.
[Editor] To initiate charging upon startup, the small wire going into the rear of the
voltage regulator must be at 12 volts. If this is grounded or disconnected (as, for
example, through a loose instrument panel or chassis connector), your alternator
will not charge. The idiot lights may or may not go on, but if they do and they
remain on, then suspect this wire or the panel connector for faults. You can also
rarely experience a flexible circuit board failure on the back of the panel. And make
sure the alternator warning lamp bulb is not burned out.
[John Randstrom] If you pull the wire off the alternator that comes from the dash
board charging lamp and ground it, the idiot light should light with the ignition in
the run position. If the lamp does not light then there is a problem with the bulb,
the ignition switch, or the wiring/instrument cluster circuit. An easy way to see if
this circuit is causing your no charge situation would be to connect a wire from the
battery positive terminal through a small spare idiot light bulb(or any bulb with the
same wattage and voltage specification) to the idiot lamp circuit connector on the
alternator. The alternator should charge and the lamp should light when the engine
is off, and go out when the alt. starts charging just like the original dash lamp
should do.
[Tip from Paul Golden] I removed my instrument cluster and did the continuity
checks, sure enough the solder joints had come loose from the wiring. I fired up
the soldering iorn and hit each solder joint with some fresh 50/50 flux core solder.
Installed the instument panel and presto, all the lights work once again. Since then
I have repaired that same problem in 6 different cars, 760, 3-960, 2-940 so it
seems to be a regular problem.
Diagnosing Alternator Exciter Circuit Troubles. [Bruce Young] The Battery,
parking brake, brake warning, and bulb failure lamps should all iluminate when the
ignition switch applies battery +12 to one side of all 4 bulbs and the other side
finds a path to ground via that small red exciter wire from the panel to:
1. alternator D+ terminal, then
2. voltage regulator, then
3. alternator brushes and slip rings, then
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4. alternator frame, then
5. Blue wire to engine ground.
These bulbs supply the required pre-excitation current to begin alternator charging:
Battery light
Parking Brake
Brake Warning
Bulb Failure
You can test for power to and thru the bulbs to the alternator D+ terminal by
taking the red wire off the D+ terminal and holding it to any engine metal (not
the alternator itself) while a helper turns the Key ON and observes the warning
lights.
Lights ON? = all is well to and thru the D+ wire
No lights = check for battery voltage at disconnected red wire end
+12V present? = battery=>cluster=>D+ wire path OK (problem is in #1 thru
#5)
No +12V = problem between battery and +12V side of cluster circuit
Installing a Replacement Exciter Circuit to the Alternator. Is it possible - and
if so, is it wise - to run a wire from the battery's + terminal to the back of the
alternator? Or, does that create a risk of damage in the long-term"? [Steve] This
information relates to my experience with the Denso 100 Amp alternator which is
on both my wife and son's 940.
It may or may not apply to other model alternators. It's possible, but not wise to
make a hard connection from the battery positive to the excitaton circuit on the
alternator. You would only do this if the circuit on the back of the flexible
instrument cluster PCB failed.
The reason(s) are:
1. You wouldn't have the convenience of a charge light to tell you that your
alternator is charging.
2. The excitation circuit (originating in the instrument cluster and going directly to
the alternator via the small red wire) powers directly to the internal voltage
regulator.
This allows the charge light to illuminate. The voltage regulator provides a circuit to
ground to excite the alternator field windings until the alternator begins charging.
After the alternator begins charging, the voltage regulator opens this circuit and the
alternator continues to provide its own field (excitation) voltage. If you connect a
wire directly from battery positive to the alternator excitation terminal, you will
have a constant drain of the battery, and probably damage the voltage regulator
over time.
On my son's 940, I did run a separate wire to the excitation terminal but not from
the battery. I ran this wire from a "switched hot" source under the dash and on to
the alternator. Inside the car, I pulled a loop of this wire out of the dashboard, cut
it, and soldered a light bulb holder for a standard 1034 12V light bulb into the
circuit. The hot wire is soldered to the terminal next to the center contact on the
bulb. This did three things: it gave me a "idiot light" to tell me if the alternator
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was charging; it provided a dependable excitation voltage source to the alternator
that would only be on when the ignition switch is on; and it provided a current
limiting device (the light bulb element) to the alternator excitation circuit. The bulb
element will handle the current that is required to excitate the alternator field.
Alternator Removal and Replacement. Disconnect battery negative and the
wires at the back of the alternator, carefully labeling each so you can replace them
at the correct terminals. See the procedure above for removal of the alternator.
See the FAQ file under Engine: Mechanical for removal of the alternator pulley.
Installing Rebuilt Alternators.
[Joe Avsec] I just installed a remanufactured NAPA alternator and one of the
housing srews vibrated loose after a couple of days. It vibrated to the point where
it came in contact with the fins on the alternator pulley, breaking all of them off
and making a terrible sound.
[Kevin O'Brien] Had the EXACT thing happen with my last rebuilt alternator: the
screw came out, put stress on the pulley, and loosened the main nut on the
alternator shaft. [Editor] This suggests you use Loctite on these screws before
installation.
Alternator Getting Weak; Regulator/Brush Replacement.
[Symptom:] The alternator on a 740T / B230 engine is getting weaker, slowly but
surely. What to do?
Bosch Alternator:
Regulator/Brush Change. [Editor] You likely need either a new regulator
(screwed into the back of the alternator) or new brushes on the existing regulator.
Swapping regulators is easy. The regulator has attached to it a set of brushes that
contact the commutator. To replace the brushes, you will need to solder the new
ones in place according to the instructions below. Also: Often the failure of an
alternator is the result of a blown diode or a worn out bearing, etc. These parts are
not expensive and their replacement is not difficult with the right tools. ($300+
alternator replacement cost for a burned out $10.00 part, what a scam!) With a
little looking, I found a shop in my area that repaired the alternators (new
bearings, brushes, leads, whatever else was needed) for about $70. All I had to do
was get the alternator out of the car and bring it to them. This may be a way to go
for your car. Note: regulators and brushes may be replaced on both Bosch and
Nipon-Denso alternators.
Inserting the Regulator Back Onto the Alternator. [Randy Starkie] To keep the
new, loger brushes from hanging up on installation, tip the assembly into place to
position the brushes before straightening it up. After you push on it to straighten it
the brushes are pushed back into the holders. Holding it in that position and then
installing the screws usually works for me.
Soldering Tips: Earlier Wires Soldered to Terminals. Drill out the brush wire
with a 1/16" bit where it is soldered to the brush holder. Brushes are available
from Volvo for less than $4.00 (probably part number 1362710 for your car- they
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can check). Solder in the new brushes and replace the regulator/brush assembly.
[Tip from Chuck Jaxel] You should use rosin-core solder specific for electrical or
electronic use. DO NOT USE PLUMBER's solder, you will create a bad connection.
Solder should have shiny appearance when it
cools, A dull gray looking finish indicates a
cold joint, another bad thing. Practice on
some old wire, find a junk radio or something
and practice on that board, its not hard, just
takes a couple of times to get it right.
[Don Foster] When you solder the heavier
alternator brush wiring, be aware that you
might need extra heat if the braid (the wire
going to the brush) is heavy, or if the
connection is large. I don't know what heat
range iron (Wattage) is in your keet, but you
might need a soldering gun (150-250 Watts)
to deliver the heat. A small iron (25 Watts) may not do it.
[Randy Starkie] There was a question about how to drill out the solder connection
to facilitate the installation of the new brushes. I have included an image here that
shows the assembly. I use a flat file to file the surface smooth. This gives a little
more definition to the target area as well as providing a good surface to get the
1/16" drill started. Since the solder is soft the drill follows the path of least
resistance removing the solder/leaving the holder intact (you will be drill towards
the brush in each case). Once the solder connection is drilled out the old brush is
released and basically pops out due to it's spring load. I apply paste flux to the
lead of each brush. If you have trouble getting your solder to stick or flow out it is
most likely because of the lack of flux. The new brushes from Volvo (part number
1362710- less than $4) have a solid wire lead on them that makes it easy to
thread them into the brush holder. Pull them down far enough that the sides of the
brush holder support the brush in an upright position. At that point bend the woven
wire at a right angle to the holder to keep each brush positioned properly. Use a
clip as shown in the photo to hold the brush gently against the spring. Apply the
heat of an iron to the junction of the brush holder and the woven wire. Take a
relatively small diameter piece of solder that has been dipped in the flux and touch
it to the brush holder where the woven wire exits. Use enough solder so that the
drill hole fills in around the woven wire (don't get over zealous here you don't want
solder dripping out the backside into the brush holders). Trim the excess wire off
and reinstall the assembly. Be sure to tilt the assembly as you position it so that
when you press the assembly into place the brushes are pushed back down into the
brush holders.
Soldering Tips: Later Wires Crimped and Soldered at Terminals. [Tips from
Don "Solder King" Foster] My '90 car has this later crimped-and-soldered
connection. First, I flowed fresh, clean solder into the crimped connection. Next, I
used a solder sucker to pull the solder out. Then I re-flowed and resucked. And
again heated the connection and rapped it on the bench to fling out the remains of
the solder. Then I was able to pull the brush out, leaving a tiny, crimped hole.
Then I reamed the hole with a tiny ice pick and several jeweler's screwdrivers 'til I
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had the hole opened sufficently. Then I threaded the insulation over the new
brushes' pigtails. Then I prepared and tinned the wire ends (new brushes) and
tack-soldered on a 2' long piece of fine wire to use as a leader. Then I threaded the
spring over the pigtail. Then I stuck the end of the leader through the narrow hole,
from the brush side, and used it to pull the pigtail through. Once I pulled enough
through, I carefully (and gently) crimped the neck with cutters and then soldered
the pigtail. I bent it over and solder about 1/8" down the outside and then cut off
the excess. (You must pull enough through so that the pigtail will hold the brush
properly in the holder but fully extended.) Before installing the VR assembly, I
cleaned the internal contacts with a pencil eraser as well as cleaning the contact in
the alternator. I also cleaned and shined up the screw ground and mating surface
on the alternator case.
Alternator Regulator/Brush Reliability. [Inquiry] Is it wise to preventatively
change out a 10 yrs old voltage regulator now?
[Response: Gary DeFrancesco] The regulators themselves are fairly robust. It is the
attached carbon brushes that wear out. If let go too far, the bushes become
ineffective and the alternator stops charging eventually. I would pull the
regulator/brush assembly out and have a look at it. If the brushes are less than
about 3/16", I would go ahead and replace the assembly. An aftermarket assembly
costs about $20. A Bosch unit runs about $50. I have installed both in my 2 745Ts
this year. So far both are working fine. My gut feel is the Bosch assembly is going
to last longer, but time will tell. I know there are those who say the brushes can
be replaced and the regulator reused. If you have the tools and want to spend the
time, go ahead. However, I do not know how much longer the electronics in the
regulator will last. With all the heat under the hood, the electronics will eventually
fail. Will they last through a second set of brushes, I don't know. So I just
bypassed the question and put in totally new assemblies. Lets face it, $50 in the
scheme of things is not a lot of money. Especially when one considers the time
involved to solder in new brushes, the cost of the brushes (I know, they're cheap),
and the cost of a big soldering iron (if you don't have one). [Response: JohnB]
Only if you can't use a soldering gun and wire snips...costs about $10 or less for a
brush kit. Prophylactically change out the brushes at 140K miles. Note that some
folks have found that aftermarket regulators can cause poor voltage regulation and
driveability problems: see Unexplained Driveability Problems: Bad Voltage
Regulator . Part numbers: 1988-1991 740 with Bosch 80 amp: Bosch regulator
1197-311-028 .
[Editor] For an older alternator, merely changing the brushes may not help much.
You should rebuild it with new bearings and turn the commutator.
If you have flickering instrument panel warning lamps, see Warning Lights
Flickering: Bad Alternator Brushes for a solution.
Nippon Denso Alternator:
Brush
and
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Regulator Parts.[Jay Simkin] Brushes: 3544588 (MSRP = $43; this number is
shown on a VADIS diagram for the 1995 940, but an on-line catalog shows it
applies only to NipponDenso units up through 1992). Voltage Regulator: 9128558
(MSRP = $160). Tasca Volvo can confirm numbers; price likely will be below MSRP.
These parts may be had from the vendors below and are very inexpensive. Have
your alternator part number at hand when you call.
Barsanco, Inc. (www.barsanco. com; 1-800-421-3374)
Brushes: 217-510
Voltage Regulator: 216-043 ; or
J & N Auto Electric
10995 Canal Rd
Cincinnati, OH 45241
(513) 771-8000
Brushes: JN50-52003
Brush Installation. [Randy Starkie] See the illustration right and the illustrated
file: the brushes in the holder assembly pictured to the right cost $2.45 or as bare
brushes for $9.95 for a pack of 50.. Installation is incredibly quick. The white hood
slides off for installation giving good access to pushing the brushes back to get the
right placement. Then just replace the white hood and reassemble.
Checking Alternator Diodes. [Tip from Corey Glassman, Electrical, Charging and
Starting System Tips and Techniques, Underhood Service, Sept 1999]
A Digital Multi-Meter's (DMM's) accuracy and digital display make
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regulator/alternator diagnosing and adjusting easy. Be aware that many of the
tests mentioned in this article may not work on your specific application. Some
alternators can be damaged by full fielding for instance, others have a pulse width
modulated field controlling charging. When in question, always follow the
manufacturer recommendations.
An alternator generates current and voltage by the principles of electromagnetic
induction. Accessories connected to the vehicle's charging system require a steady
supply of direct current at a relatively steady voltage level. You cannot charge a
battery with alternating current, so it must be rectified to direct current.
Checking Ripple Voltage
Ripple voltage or AC voltage can leak past the rectifier bridge diodes and actually
cause the battery to discharge. It can be measured by switching your DMM to AC
and connecting the black lead to a good ground and the red lead to the BAT
terminal on the back of the alternator. Do not connect the leads to the battery, as
the battery will absorb or dampen some of the AC. Run the engine at 2,000 rpm
and read the meter's display.
You may want to also load the system by turning on the rear window defogger and
headlights. A good alternator should measure less than 500 mV (.5 VAC). A higher
reading indicates damaged alternator diodes and may cause problems in the ECU.
Another way to check the integrity of the diodes on a Bosch regulator is to check
the voltage readings at the D+ terminal and B+ terminal. The voltage reading
should be the same at both terminals. A difference of more than one volt would
indicate faulty diodes and the need to replace the regulator.
Use the Vehicle's Radio to Check Alternator Diodes
Have you ever heard a whine from the radio that changes with engine rpm and
isn't rap music? You can use the vehicle's radio to test the alternator's diodes. Turn
on the radio and select a quiet FM radio station. Turn up the volume and rev the
engine from idle to 2,000 rpm and back down to idle. Listen for a small whine or
siren noise in the background that follows the rpm change. The noise usually
indicates excessive ripple or AC voltage leakage from the rectifier bridge diodes.
Verifying a Good Alternator
The battery must be fully charged before testing the alternator. Run the engine and
verify that the no-load voltage is 13.8 to 15.3 V. Next, load the alternator to its
rated output current with a carbon pile across the battery. If you don't have a
carbon pile, load the alternator by turning on as many accessories as you can. Run
the engine at 2,000 rpm and check the current output with a current clamp. You
may find that someone has put a number of additional loads on the charging
systems increasing current demand from the alternator. Make sure that the
alternator is rated to the application.
Where Is the Best Ground?
Technicians ask me this all the time. With the engine shut off, the battery supplies
power to accessories and is the source of the best ground. After the engine starts
and the alternator takes over, the alternator becomes the source of all power and
the battery becomes a load and stabilizer. The best ground now is on the alternator
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case, located at the grounding point for the brush set, rectifier bridge and in some
cases, the regulator. Where are they mounted? On the rear case half, and how is
the rear case half attached to the front? Typically with four through bolts
sandwiching the field between them. Most alternators use the front case half as the
mount for the belt adjusters and block attachment. With the engine running, it is
always a good idea to measure a voltage drop between the front and rear case
halves to ensure great connections.
Testing Alternator/Battery Voltage and Amps.
Battery Load Test:
[Motor Magazine, Apr 2002] A load test indicates how well a battery can deliver
current while still maintaining enough voltage to operate the ignition system. This
is generally the preferred test for any battery in a late-model vehicle. A battery
must be at least one-half to three-quarters charged for an accurate load test-
preferably fully charged. A load test places a specific current load on the battery to
indicate how it will perform under heavier demands, such as cranking. A good
battery should deliver the specified current while maintaining a voltage of 9.6 volts
or more for 15 seconds at 70 F. As noted earlier, a cold battery delivers less
current than a warm one, so the minimum voltage specs must be compensated for
temperature. At 30 F, minimum voltage drops to 9.1 volts; at 0 F, it's 8.5 volts. If
you have a digital voltmeter with Min/Max recording capability, you can do a fast
load test that yields quite reliable results. First, connect your voltmeter across the
battery and select the Min/Max recording function. Now turn on the headlights and
crank the engine until it starts. Finally, let the engine run for about 10 seconds,
then shut it down. The minimum recorded voltage on your meter is the lowest
voltage reached by the battery during cranking. The maximum recorded reading is
the alternator recovery voltage after the engine started.
Charging Amps:
With the engine idling and no load on the charging system (lights and all
accessories off, battery fully charged), the amperage output should be relatively
low (typically less than 10 amps). With the headlights and heater blower fan on
and the engine running at 2,000 rpm, the output should jump to a higher reading,
typically 25-30 amps or more. Charging voltage varies according to underhood
temperatures. Room temperature charging voltage is generally about 14.2 volts. As
underhood temperatures increase, charging voltage drops down to about 13.8
volts. In very cold climates, charging voltage may temporarily increase to 14.8 or
perhaps 15.0 volts.
Voltage Drop in Cables:
Test the voltage drop in the battery cables to ensure that corrosion or internal
failures are not preventing a charge. [Tip: Jim Bowers] There should be less that
0.2 volt drop from the alternator to the battery + terminal. My car had a bad crimp
on the lug at the alternator and after I bought it I had no-starts due to a depleted
battery. After starting the engine while the battery was recharging, I measured 0.5
volts from the alternator stud to the wire just after the lug. I cleaned and soldered
the crimp lug and while I was at it also replaced the regulator/brush assembly. I've
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had no battery problems for 5 years now.
Cautions:
Don't trust your volt meter in the instrument panel ! Always check voltage at the
alternator & battery. If that alternator is weak you'll notice a drop in fuel economy
because the fuel system tends to go rich as a battery dies. I replace around 40
voltage regulators in a year, and maybe 2 alternators. Be careful of chain repair
operations, gas stations and tow-truck operators: Pep boys technician : "I'll do a
quick battery test." Technician disconnects battery with ignition on and engine at
high idle . Result: INSTANT $865.00 DAMAGE, blowing five relays, radio and other
electrical equip. NEVER disconnect battery with engine running!
Alternator Wiring is Failing. [Editor's Note: See the section on Baked Wiring
Harnesses in Electrical: Circuits, Relays for more information.] One quick thing to
check is the ground wire that goes from the alternator to the engine block. That
broke on me, resulting in my running off the battery with the same symptoms you
have. It was not until I pulled the alternator that I saw the broken wire. Would
have saved a lot of time to check that first. I have been through this on so many
cars that whenever it happens, and the battery proves to hold a charge, I
automatically yank the alternator and head straight for the local rebuilder. I
couldn't tell for sure at first which alternator I had-turned out to be Bosch internal.
I don't remember how much to rebuild, but it was considerably under $100.
[Symptom: idiot lights all go on; also, oil pressure gauge is erratic:] Having all the
idiot lights go on at once is not as strange as it might seem. This will happen if the
small wire leading to the back of the alternator is grounded. It will also happen if
the alternator is not generating any current. When this wire is at ground potential,
it is the same condition as before you start the car - hence the idiot lights are on
so you can check they are not burned out. The wires for the alternator and also the
o/p sender go around the front of the engine under the main crank pulley. (If you
get under the front you will see what I mean.) Dripping crank seals often get oil all
over these wires. Not to mention it is hot by the alternator. Flaky insulation may be
at work. If you really want, you can reroute these wires around the right side of
the car instead and splice into the harness at the firewall.
Alternator Interchange. [Randy Starkie] My experience is that there are three
different alternators used on the 7/9 series cars. The older ones use the Bosch with
the regulator and brush assembly that is also used in the 240's.The two 1994
944Ts we have use the newer Bosch (Denso type) marked as made in Great
Britain- part number 9130275 (shown as superseded by 8111115).The 1992 745
has a small 100 amp Denso alternator part number 3544119 (shown as
superseded by 8251744).The question (finally) is do these units interchange? Is the
mounting hardware similiar enough that if I were to get one of the small 100 amp
Denso and its mounting hardware could I install it on amy of the cars mentioned?
[John Sargent] They all interchange. The later alternators use a larger stud on the
output terminal, and you'll have to carefully ream out the lug on the earlier cars, or
replace the lug. The small Nippondenso unit is supposed to have better voltage
regulation.
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Battery, Terminals, and Wiring:
Slow Battery Discharge. [Inquiry:] I am having an electrical problem with my
Volvo. About two months ago the battery went dead--slowly over time. It was an
old battery, so I though nothing of it and replaced it. All was good for a month and
a half, then it went dead again. With the car running I measured 14volts across the
terminals of the battery (12 when stopped) and 14v off the main positive lead of
the alternator. What is the problem here?
Resources. See this useful site for diagnostic ideas.
[Battery Drain Diagnostics: Response: Ross Gunn] To check to see if there is
something draining the battery while the ignition key is removed, remove the
positive battery terminal, and with a digital electronics meter set to "amps",
measure to see if there is any current flowing between the battery terminal and
the cable end. For more accuracy, use a low-amp induction probe ammeter to
measure current flow through the battery cables. If there is anything more than a
couple of milliamps, re-connect the cable and remove fuses one at a time to see if
you can identify the circuit that is causing the drain. If this pins down a problem, a
little more sleuthing through the offending circuit should tell you what needs to be
done.
If there is no drain showing with the above test, the charging system is suspect.
Try measuring the voltage at the alternator output terminal and battery pos
terminal with all utilities (headlights, rear window heater, fan etc.) on high. Any
difference in reading indicates a poor connection somewhere in the red cable from
the alternator. Don't assume that a crimp connection of a terminal on the cable is
good. Corrosion can introduce enough resistance to prevent proper (any?) charging
when there is a significant load on the system (cold, dark, wet/snowy winter
evenings). I have experienced this on a 20 year old Brick.
[Battery Drain Diagnostics: Chris Bowne] I agree with Ross Gunn that the best
way to trouble shoot a discharging battery is to find the source with the engine
shut down and a multimeter (set to measure DC current) in series with the positive
battery terminal lead. Other places to check besides the fuse block for drain paths
are the alternator and voltage regulator (if not internal to the alternator).
Disconnect/reconnect the connections on them, one at a time, and monitor for
drain. I had a problem on a Ford Taurus once where the voltage regulator had
shorted, and was the cause of the drain. You may or may not find a source of a
drain like this merely by pulling fuses. In fact, you could end up with all the fuses
pulled, and still have the drain, like I did!
Someone on an earlier posting of this thread mentioned checking to see if his
alternator was providing output by lifting the battery + terminal connection WITH
THE ENGINE RUNNING. DO NOT DO THIS! Many solid state regulators will be
damaged/destroyed by this condition. (And in turn may compound the causes of
the battery drain you are troubleshooting!)
Battery Tips. [Tip from JohnB] Check the specific gravity of the cells...if they're
accessible. With a fully charged battery, either from your battery charger or the
alternator, disconnect the battery and measure the voltage, measure it again 12
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hours later and it should be virtually the same, maybe .1v less, no more.
Reconnect the battery to the car and turn on the headlights on full bright for 10
minutes and every accessory in the car...if the battery dies in 10 minutes replace
the battery. Otherwise, battery voltage should remain above 10.5 volts or so after
this test. There are load testers available in auto parts stores for about $30 or so
that will do a higher load test (couple hundred amps through a resistance load
bank) in about 10-30 seconds against a red/bad yellow/weak green/good voltage
scale. If these tests still have you with a good battery, then you just have to trace
down the current drain, circuit by circuit.
Tool Tips for Short Circuits. See the Special Tools section of the FAQ for
suggestions on tools capable of rapidly locating shorts in wiring harnesses. [George
Downs] Take a fuse, remove the element, and solder an instrument light bulb
across it. With the engine off, plug it in to each circuit in turn at the fuse panel and
find the one that illuminates it. That is the circuit which is grounding your battery
and causing the drain.
Starting Problems and Battery Cable/Terminal Corrosion.
Terminal Corrosion and Starting Problems:
[Inquiry:] Car cranks strongly but will not start.
[Response 1: Jim Rothe] I've been discounting -- actually, completely ignoring --
any possibility of battery terminal corrosion, mostly because I've always had strong
cranking power. But in light of last night's incident (and the prior one time
occurrence) of starting with the help of a jump start, I'm going to re-check these
things. I'm reminded of incidents with my RX-7 last year, when I was able to crank
it strongly and it wouldn't start. I replaced the battery a few weeks later when the
starter motor started sounding weak, and then my intermittent no-start condition
miraculously disappeared. I've since found out that early rotaries tended to be a bit
more susceptible to weak sparks (compounded by old, low compression, engines)
than other cars. Food for thought.
[More Battery Cable Tips from Paul Grimshaw] The battery grounding cable on
Volvo 700-series cars fitted with the 2.3 litre engine is constructed of braided steel,
crimped to lugs which secure it in place. Over time, chassis and engine bay
vibrations may weaken the grounding wire. This often breaks at the block
connection. Furthermore, the effects of salt-induced corrosion can adversely affect
the crimped portion at the lugs--resulting in a poor electrical contact. Any ground
failure, whether total or partial, can play havoc with electronic systems and can
lead to the failure of the car's engine management computer and/or mass airflow
sensor. Given the risk of failure of this part, it's advisable to regularly inspect the
ground cable.
Preventive Maintenance. [Eric Anderson] . I work for Lockheed and spent years
chasing micro-corrosion. MicroC exists everywhere and is aggravated by substantial
temperature changes. It is a microscopic or larger film of corrosion that can build
up on both positive and ground connections with a preference to the ground
connection, however auto's positive connection are just as susceptible. Have you
thoroughly cleaned the battery connections, tightened and applied an anti-corrosive
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(exide cro-guard, etc)? removed the starter B+ (positive cable) and brush the lug
and the stud it attaches to plus all washers and mounting points. retightend and
apply antiC? Same applies to ground connections. [Editor] For years, I have used
the little colored fabric washers (red/green) that go under the battery terminals to
prevent corrosion. They really do work, especially when combined with an anti-
corrosion spray (the little cans of red spray you can buy at Walmart). Never, ever
had a corroded battery terminal or wire set.
Diagnosing Corroded or Malfunctioning Cables and Wiring Using the
"Voltage Drop" Method:
[Motor Magazine Mar 04] Measuring the resistance from one end of the cable (the
battery) to the other end (the starter) will not reveal a problem. That's because
your Digital MultiMeter places an almost unmeasurable load on the cable when it
measures its resistance. Because the load is so small, the DMM will show a very
low resistance reading, as long as even just a few of the strands in the battery
cable are still good. The DMM can't tell the difference between a good cable and a
bad one with this test. What's needed is a test that will reveal the cable's
performance when it's in operation and under a load. To test the negative battery
cable, attach the DMM's negative lead to the negative battery terminal. Don't
attach it to the terminal clamp; we want to test the whole circuit from end to end.
Attach the positive DMM lead to the starter motor body or the engine block. Set the
DMM to the 0-40 volt DC scale, then have an assistant crank the engine while you
watch the DMM display. Any voltage reading shown represents the voltage that has
been dropped between the battery and the starter motor. Typically, a ground cable
that's in good condition will drop .1 volt or less. Don't accept a voltage drop that's
greater than .3 volt. A cable that's causing starting problems may be dropping far
more than even these modest amounts. Voltage drops may occur at any point in a
circuit. It may not be practical to replace all of the suspect wiring, so it will be
necessary to pinpoint exactly where the voltage drop is occurring. It's relatively
easy with something like a battery cable because there are only a few joints or
connections in the circuit. If there's a voltage drop, the likely suspects are the cable
itself or the terminals at each end. Cleaning the connections and replacing the
cable should take care of the problem.
When a circuit is longer and more complicated than a battery cable, save time and
keep your diagnosis focused by using the split half method. Divide the circuit in
half, then perform a voltage drop test on one half at a time. Find a convenient
connector somewhere in the middle of the circuit to mark your halfway point.
Conduct a voltage drop test on the front half of the circuit while it's under load. If
no significant voltage drop is found, move to the rear half of the circuit, then
retest. Keep dividing the remaining segments of the circuit in half until you've
narrowed it down and have conclusively located the voltage drop. Many circuits on
today's vehicles are designed to carry very low voltage and amperage. Ohm's Law
reminds us that any added resistance in these circuits will have a direct effect on
their ability to perform as designed. Voltage drops measured in tenths or even
hundredths of a volt can be significant and will cause problems.
Cleaning Battery Posts and Connectors:
[Editor] You can clean the battery posts and cable connectors safely by:

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