CDI 174-8778K 1 Guide

Installation and Troubleshooting Guide
This installation is to be completed by an Authorized Dealer or Professional Service
Technician. For questions regarding installation or warranty, call CDI Tech Support
at 866-423-4832. Do not return to the Dealer or Distributor where the part was purchased.
Contact CDI Electronics Directly for Return Material Authorization.
CDI Electronics, LLC •353 James Record Road SW •Huntsville, AL 35824 USA
Web Support: www.cdielectronics.com •Tech Support: 1-866-423-4832 •Order Parts: 1-800-467-3371
All rights reserved. Reproduction or use of content, in any manner, without express written permission by CDI Electronics, LLC., is prohibited.
Rev H •6/19/2023 Page - 1 of 4 QF-358
CDI P/N: 174-8778K 1
This unit replaces the following 2, 3, and 4 cylinder P/N's: 398-818535A 3, 5, 8, 9,10,13,14, 15, and 31; 398-8778A6, 10, 16, 17, 18, 21, 22,
23, 24, 25, 26, 27, 28, 29, and F749095.
Warning! This product is designed for installation by a professional marine mechanic. CDI Electronics cannot be held liable for
injury or damage resulting from improper installation, abuse, neglect, or misuse of this product.
It is recommended that dielectric grease (i.e. CDI 991-9705) be used in the bullet nose connectors to help prevent corrosion.
Any sign of leakage out of the high voltage coils or bubbling around the battery charge windings indicate a bad Stator. Check for burned
marks on each pole. If a problem is found on the battery windings, we recommend the Rectifier be closely checked. To replace Stators with
ring terminals, please use the fork terminals enclosed with this Stator.
If this Stator is to be used as a replacement for the Mercury “Red”Stator, connect all wires to the Switchbox in their designated
position. The Adapter Module used with the Red Stator is no longer needed.
If this Stator is to be used on a 3 cylinder engine, connect the Red/white and Blue/white striped wires to engine ground.
This Stator can be used with either a 9 amp Rectifier or a 16 amp Voltage Regulator.
INSTALLATION
1. Disconnect the Negative battery cable.
2. Disconnect the Stator wires from the Switchbox, engine ground, and the Rectifier.
3. Remove the flywheel according to the service manual for your engine.
4. Mark the position of the mounting screws in relation to where the Stator wires come out of the old Stator and remove the old Stator.
5. Orient and install the new Stator (using a good thread locker applied to the bolts) in the same position as the old Stator on the engine
and install the flywheel, following the service manual instructions.
6. Connect the Yellow wires from the Stator to the Rectifier, ignoring any stripes on the Regulator’s Yellow wires.
7. Connect the Stator leads as follows:
New Stator 2 Cylinder Switchbox 3 Cylinder Switchbox 4 Cylinder Switchbox
Red(High speed Coil) Red (High speed Coil) Red (High speed Coil) Red (High speed Coil)
Blue (Low speed Coil) Blue (Low speed Coil) Blue (Low speed Coil) Blue (Low speed Coil)
Red/White (High speed Coil) Red/White (High speed Coil) Engine Ground Red/White Stripe (High speed Coil)
Blue/White (Low speed Coil) Blue/White (Low speed Coil) Engine Ground Blue/White Stripe (Low speed Coil)
7. If this Stator is to be used on a 3 cylinder engine application, connect the Red/White and Blue/White striped wires to a known good
engine ground.
8. If using this Stator on an application that uses a Switchbox with stud connections, it will be necessary for you to remove the female
bullet connectors attached to the Blue, Blue/White, Red, and Red/White wires that are preinstalled from the factory and install the fork
terminals that come supplied in the kit provided with the Stator. Crimp or solder the fork connectors to the Blue, Blue/White, Red, and
Red/White wires.
9. If your engine used a Mercury Red Stator Kit, it is normal for that application to have NOT used the Red and the Red/White wire (or
Red and Red/White stud post on a studded Switchbox). These are usually either taped up or capped off. With the CDI Electronics 194-
8778K 1 Stator, the Red and Red/White wire WILL be used. Find the Red wire (or Red stud post on a studded Switchbox) and connect
the Solid Red wire from the New Stator to the Switchbox. On a 2 and 4 cylinder application, connect the Red/White wire to the
Switchbox in its appropriate place. On a 3 cylinder application, connect the remaining Red/White and Blue/White striped wires to a
known good engine ground.
10.Replace the flywheel according to the service manual.
11. Connect the Negative battery cable.

Installation and Troubleshooting Guide
This installation is to be completed by an Authorized Dealer or Professional Service
Technician. For questions regarding installation or warranty, call CDI Tech Support
at 866-423-4832. Do not return to the Dealer or Distributor where the part was purchased.
Contact CDI Electronics Directly for Return Material Authorization.
CDI Electronics, LLC •353 James Record Road SW •Huntsville, AL 35824 USA
Web Support: www.cdielectronics.com •Tech Support: 1-866-423-4832 •Order Parts: 1-800-467-3371
All rights reserved. Reproduction or use of content, in any manner, without express written permission by CDI Electronics, LLC., is prohibited.
Rev H •6/19/2023 Page - 2 of 4 QF-358
TROUBLESHOOTING
How to test the Engine Stop Circuit (Kill) for DC Voltage:
1. DC voltage present on the kill circuit of the Switchbox due to a faulty key switch, boat harness, or engine harness will severely damage
the Switchbox’s internal kill circuit. Connect a Digital Multi Meter to the Ignition Stop wire(s) AT THE SWITCHBOX while disconnected
from the Switchbox in reference to a known good engine ground. Turn the Ignition switch on and off several times. If, at any time, you
see over 2 VDC on the kill wire(s), there is a problem with one or both harnesses and/or the Ignition switch. The Ignition Stop wire
should not be connected back to the new Switchbox at any point until the problem is corrected OR DAMAGE TO THE SWITCHBOX
WILL OCCUR!
NO SPARK ON ANY CYLINDER:
1. Perform a visual inspection of the Stator and Trigger wiring to the Switchbox. Check to make sure that the wiring is correct, clean, and
free of corrosion, and that all connections are tight.
2. Disconnect the Black/Yellow kill wire AT THE SWITCHBOX and retest. If the engine’s Ignition now has spark, the stop circuit has a
fault. Check the key switch, harness, and shift switch (if present).
3. Disconnect the Yellow wires from the Stator to the Rectifier and retest. If the engine now has spark, replace the Rectifier.
4. Check the cranking RPM. A cranking speed less than 250 RPM will not allow the system to spark properly. This can be caused by a
weak battery, dragging starter, bad battery cables, or a mechanical problem inside the engine.
5. Check the Stator and Trigger resistance and DVA for your engine in the lists below:
Check the 2 cylinder engine as follows:
Read from Read to Ohms DVA (Connected) DVA (Disconnected)
Blue (Low speed Coil) Blue/White (Low speed Coil) 500-700 Ω180 V Minimum 180 V Minimum
Red(High speed Coil) Red/White (High speed Coil) 28-32 Ω25 V Minimum 25 V Minimum
Purple (#1 Trigger) White (#2 Trigger) 0.8-1.4K Ω4 V Minimum 4 V Minimum
Purple (#1 Trigger) Engine Gnd Open 1 V Minimum -
White (#2 Trigger) Engine Gnd Open 1 V Minimum -
Check the 3 cylinder engine as follows:
Read from Read to Ohms DVA (Connected) DVA (Disconnected)
Blue (Low speed Coil) Engine Gnd 500-700 Ω180 V Minimum 180 V Minimum
Red(High speed Coil) Engine Gnd 28-32 Ω25 V Minimum 25 V Minimum
Brown (Trigger) (a) White/Black (or Black) (Trigger) 0.8-1.4K Ω 4 V Minimum 4 V Minimum
White (Trigger) (a) White/Black (or Black) (Trigger) 0.8-1.4K Ω 4 V Minimum 4 V Minimum
Purple (Trigger) (a) White/Black (or Black) (Trigger) 0.8-1.4K Ω 4 V Minimum 4 V Minimum
Brown (Trigger) (a) Engine Gnd Open 1 V Minimum -
White (Trigger) (a) Engine Gnd Open 1 V Minimum -
Purple (Trigger) (a) Engine Gnd Open 1 V Minimum -
NOTE: The 3 cylinder engines have several configurations to the firing order. Please refer to the Factory Service Manual to
make that determination. The pairing should always be as follows:
•Green Coil Wire goes with the Brown Trigger Wire
•Green/Red Coil Wire goes with the Purple Trigger Wire
•Green/White Coil Wire goes with the White Trigger Wire
Check the 4 cylinder engine as follows:
Read from Read to Ohms DVA (Connected) DVA (Disconnected)
Blue (Low speed Coil) Blue/White (Low speed Coil) 500-700 Ω180 V Minimum 180 V Minimum
Red(High speed Coil) Red/White (High speed Coil) 28-32 Ω25 V Minimum 25 V Minimum
Purple (#1 Trigger) White (#2 Trigger) 0.8-1.4K Ω 4 V Minimum 4 V Minimum
Brown (#3 Trigger) White/Black or Black (#4 Trigger) 0.8-1.4K Ω 4 V Minimum 4 V Minimum
Purple (#1 Trigger) Engine Gnd Open 1 V Minimum -
White (#2 Trigger) Engine Gnd Open 1 V Minimum -
Brown (#3 Trigger) Engine Gnd Open 1 V Minimum -
White/Black (#4 Trigger) Engine Gnd Open 1 V Minimum

Installation and Troubleshooting Guide
This installation is to be completed by an Authorized Dealer or Professional Service
Technician. For questions regarding installation or warranty, call CDI Tech Support
at 866-423-4832. Do not return to the Dealer or Distributor where the part was purchased.
Contact CDI Electronics Directly for Return Material Authorization.
CDI Electronics, LLC •353 James Record Road SW •Huntsville, AL 35824 USA
Web Support: www.cdielectronics.com •Tech Support: 1-866-423-4832 •Order Parts: 1-800-467-3371
All rights reserved. Reproduction or use of content, in any manner, without express written permission by CDI Electronics, LLC., is prohibited.
Rev H •6/19/2023 Page - 3 of 4 QF-358
6. Inspect the flywheel Trigger and Stator magnets to see if they are loose or broken. Disconnect the Rectifier and retest. If the spark
returns, replace the Rectifier.
7. Disconnect Red and Red/White wires and retest. If the DVA tests above is withing specifications, the Switchbox is usually bad.
NO SPARK ON 2 CYLINDERS (4 CYLINDER ENGINE):
1. DVA test Stator (see NO SPARK ON AN CYLINDER).
2. Swap the Blue with the Blue/white Stator leads, and the Red with the Red/white Stator leads to see if the no spark problem changes. If
it does, the Stator is bad. If the problem remains on the same cylinder(s), the Switchbox or Trigger is probably at fault.
HIGH SPEED MISFIRE OR WEAK HOLE SHOT:
1. Connect DVA meter to the Blue and Blue/white wires and do a running test. The voltage should show a smooth climb and stabilize,
gradually falling off at higher RPM's (above 3,000). If you see a sudden drop in voltage right before the miss becomes apparent, the
Stator is likely at fault.
2. Connect DVA meter to the Red and Red/white wires. The voltage should show a smooth climb throughout the RPM range, a sudden
drop or decline in voltage indicates a problem usually found in the Stator, although a Rectifier can cause the same symptom.
3. Disconnect Rectifier and retest. If the problem disappears, replace the Rectifier and retest.
4. Rotate the Stator one bolt hole in either direction and test. If the miss is gone, leave the Stator as is. If the miss is the same or worse,
rotate the Stator back where it was.
ENGINE WILL NOT STOP (KILL):
1. Disconnect the Black/Yellow (or Orange) wire(s) at the Switchbox. Connect a jumper wire to the stop wire from the Switchbox and short
it to engine ground. If this stops the Switchbox from sparking, the stop circuit has a fault. Check the key switch, harness, and shift
switch (if present). If this does not stop the Switchbox from sparking, replace the Switchbox.
BATTERY CHARGING ISSUES:
1. Regardless of whether the charging issue is overcharging or not charging at all, the #1 cause of all charging issues is the battery often
due to improper style and/or charging neglect. #2 is the battery’s connections. #3 is the Rectifier. #4 is the Stator.
2. The recommended type of battery for outboards is a single (NOT more than one) 850+ CCA dual purpose or cranking/starting non-
maintenance-free battery.
3. Non-maintenance-free batteries (lead-acid flooded cell; has vent caps on its top) have heavy, thick plates. They’re ideal for outboards,
where batteries are commonly drained by accessories while fishing, etc. when there is no charge applied to a battery while the battery
is in use. Its heavy plates can withstand constant discharging and charging. These batteries have much more reserve time and are
much more suited for this behavior.
NOTE: Some Maintenance free batteries will have vented caps on top. When in doubt, change the battery to a non-
maintenance free type.
4. Maintenance-free batteries should NEVER be used in an Outboard application. A new, fully charged maintenance-free battery may
work fine at first but their life span is dramatically shortened due to the constant charging and discharging. This activity will cause the
cells to become weak, and/or the cells will become dead. When this happens, the battery is unable to accept a full charge, thus putting
the Regulator at extreme risk of failure. Therefore, maintenance-free style batteries commonly cause charging issues shortly after
installation.
5. Check all battery connections, particularly at engine ground. Make sure that all connections are tight and free of corrosion. Do NOT use
wing nuts as they tend to loosen over a period of time from vibration. A loose connection WILL cause a premature battery and/or
Rectifier failure(s).
6. If there is no change, try a single (NOT more than one) known good fully charged battery that is 850+ CAA Dual Purpose, or a
cranking/starting battery that is non-maintenance free. Make sure the battery is a lead acid flooded cell battery (has vent caps on its
top).
7. Measure the DVA across the Stator’s Yellow battery charge wires, while connected to the Rectifier. At idle the DVA will normally
between 8-25 DVA. If not, disconnect the Yellow wires from the Rectifier and retest. DVA will normally be 17-50 DVA at idle. If the
voltage is low, the Stator is possibly faulty. Perform a visual of the Stator for browning and varnish dripping. These are signs that the
Stator has overheated. If the visual inspection shows any of these signs, replace the Stator.

Installation and Troubleshooting Guide
This installation is to be completed by an Authorized Dealer or Professional Service
Technician. For questions regarding installation or warranty, call CDI Tech Support
at 866-423-4832. Do not return to the Dealer or Distributor where the part was purchased.
Contact CDI Electronics Directly for Return Material Authorization.
CDI Electronics, LLC •353 James Record Road SW •Huntsville, AL 35824 USA
Web Support: www.cdielectronics.com •Tech Support: 1-866-423-4832 •Order Parts: 1-800-467-3371
All rights reserved. Reproduction or use of content, in any manner, without express written permission by CDI Electronics, LLC., is prohibited.
Rev H •6/19/2023 Page - 4 of 4 QF-358
MAXIMUM OUTPUT TEST:
1. Install an ammeter capable of reading at least 9 Amps between the Red wire and the starter solenoid battery post.
2. Connect a load bank to the battery.
3. In the water or on a Dynamometer, start the engine and bring the RPM up to approximately 4500 RPM in gear.
4. Turn on the load bank switches to increase the battery load to equal 9 Amps.
5. Check the ammeter.
6. If the amperage is low,
a) Check the load bank connections and meter for battery draw.
b) If the output is still low, check and clean all connections between the battery and the Rectifier. Inspect the Stator windings for
burned or discolored windings.
7. If the amperage is correct, but the battery voltage remains low, replace the battery.
TACHOMETER TESTS
1. Measure the DVA across the Stator’s Yellow battery charge wires, while connected to the Rectifier. At idle the DVA will normally be
between 8-25 DVA. If not, disconnect the Yellow wires from the Rectifier and retest. DVA will normally be 17-50 DVA at idle. If the
voltage is now within specification, the Rectifier is likely defective.
2. Disconnect the Rectifier’s Gray wire. At 800-1,000 RPM, check the DVA on the Gray wire FROM THE RECTIFIER measured to engine
ground. The reading should be 8 DVA or more. If not, replace the Rectifier.
3. If at least 8 DVA, run a jumper wire from the Gray wire out of the harness to one of the Stator’s Yellow wires.
4. If still no tachometer signal, try a known good tachometer.
5. If still no tachometer signal, replace the Stator.
OVERCHARGING:
1. Clean all battery terminals, cables, and mounting bosses.
2. Check the voltage on the battery with a multi meter and compare it to the dash meter.
3. Compare the voltage at the Rectifier with the voltage at the battery. If the voltage is ok at the Rectifier and not good at the battery, you
have a bad connection somewhere. Clean the battery posts and terminals.
4. Replace the battery with a known good Maintenance type flooded wet lead acid marine battery. If the battery voltage remains ok, install
a new Maintenance type flooded wet lead acid battery.