Volvo TAD650VE Instruction manual

Workshop Manual
Group 30
TAD650VE, TAD660VE,
TAD734GE, TAD750VE, TAD760VE
I
4(0)

Group 30 Electrical system
Industrial Engines
TAD734GE, TAD650VE, TAD660VE, TAD750VE,
TAD760VE
Contents
Safety rules ............................................................ 3
General information .............................................. 4
About this Workshop Manual ............................... 4
Spare parts .......................................................... 4
Certified engines .................................................. 4
Repair instructions ................................................ 5
Our common responsibility................................... 6
Tightening torques ............................................... 6
Special tools ......................................................... 7
EMS 2 - “Engine Management System” .............. 8
General information .............................................. 8
CAN - Controller Area Network ............................. 8
CIU - Control Interface Unit .................................. 9
DCU - Display Control Unit ................................... 9
Fuel control ........................................................ 10
Calculation of fuel quantity ................................. 10
Altitude correction .............................................. 10
Diagnostic function ............................................ 10
Component location ........................................... 11
TAD 650, 660, 750, 760 VE ............................... 11
TAD 734 GE ...................................................... 12
Component description ...................................... 13
Starter motor ...................................................... 13
Alternator ........................................................... 13
Injectors ............................................................. 14
Speed sensor, crankshaft .................................. 14
Speed sensor, camshaft .................................... 14
Sensor, boost pressure/
boost temperature .............................................. 15
Sensor, oil pressure, engine ............................... 15
EGR ................................................................... 15
Coolant temperature sensor ............................... 16
Sensor, common rail pressure (fuel) ................... 16
Sensor, fuel pressure ......................................... 16
Magnetically controlled proportional valve
(MPROP) ........................................................... 17
Water in fuel switch, secondary fuel filter .......... 17
Switch, coolant level .......................................... 17
Preheater ........................................................... 18
Engine control unit, EMS 2 ................................ 18
Repair instructions .............................................. 19
General advice on working with EMS engines .... 19
Electric welding .................................................. 20
Changing the engine control unit ........................ 21
Reprogramming a control unit............................. 22
Programming an empty control unit .................... 23
Fault tracing of cables and connectors ............... 24
Checking the starter motor voltage..................... 26
Checking the charging system ........................... 27
Rail pressure measurement................................ 28
Malfunctions ........................................................ 29
Fault code information........................................ 29
FMI table / SAE standard .................................. 30
Manual fault tracing in bus cables ...................... 33
Diagnostic Trouble Codes .................................. 34
MID 128, PID 45
Inlet air heater status ......................................... 34
MID 128, PID 94
Fuel pressure ..................................................... 37
MID 128, PID 97
Water in fuel ....................................................... 43
MID 128, PID 100
Oil pressure ....................................................... 46
MID 128, PID 105
Boost temperature ............................................. 52
MID 128, PID 106
Boost pressure................................................... 58
7747632 English 03–2007

© 2007 AB VOLVO PENTA
We reserve the right to make modifications without prior notice.
Printed on environmentally compatible paper.
MID 128, PID 108
Ambient air pressure .......................................... 64
MID 128, PID 110
Coolant temperature ........................................... 66
MID 128, PID 111
Coolant level ...................................................... 72
MID 128, PID 158
Battery voltage................................................... 76
MID 128, PID 164
Rail pressure ...................................................... 78
MID 128, PID 190
Engine speed ..................................................... 84
MID 128 / MID 144, PPID 4
Start input CIU ................................................... 85
MID 128 / MID 144, PPID 6
Engine stop switch ............................................. 87
MID 128, PPID 19
Internal EGR status ........................................... 89
MID 128, PPID 55
EMS temperature ............................................... 93
MID 128, PPID 98
Engine sync acknowledge .................................. 95
MID 128 / 144, PPID 132
Throttle input request failure, DCU/CIU .............. 97
MID 128, SID 1-6
Injector common rail # 1-6 .................................100
MID 128, SID 21
Speed sensor camshaft ....................................105
MID 128, SID 22
Speed sensor, crankshaft ................................. 110
MID 128, SID 39
Engine starter relay ...........................................115
MID 128, SID 42
Injection control pressure regulator....................118
MID 128, SID 70
Preheat sense ...................................................122
MID 128, SID 211
5V sensor supply 2 ...........................................124
MID 128, SID 231
Communication fault J 1939 ..............................126
MID 128, SID 232
5V sensor supply 1 ...........................................129
MID 128, SID 240
Program memory .............................................. 131
MID 128, SID 254
Controller error ..................................................132
MID 128, PSID 96
Rail pressure system ........................................133
MID 128, PSID 97
Rail pressure release valve ...............................137
MID 128 / MID 144, PSID 201
J1939 communication bus ................................141
Engine protection ..............................................144
TAD 650, 660, 750, 760 VE .............................. 144
TAD 734 GE .....................................................145
Wiring diagrams................................................. 146
Wiring diagram EMS 2:
Vechicle harness TAD 650-760VE ................... 146
Engine harness TAD 650-760VE ...................... 147
Engine harness TAD 734GE ............................148
Wiring diagram DCU .......................................... 149
Wiring diagram CIU ...........................................150
Technical data ....................................................151
Switch, water in fuel ..........................................151
Sensor, fuel pressure ........................................151
Speed sensor, camshaft /
Speed sensor, crankshaft ................................. 151
Sensor, oil pressure .......................................... 151
Sensor, rail pressure ......................................... 151
Combination sensor,
boost pressure/boost temperature .....................152
Sensor, coolant temperature .............................152
Switch, coolant level ......................................... 152
Alternator ..........................................................152
Starter motor .....................................................152
Index ...................................................................153
References to Service Bulletins ........................153

Group 30: Electrical system Safety information
3
Safety rules
Introduction
This workshop manual contains technical data, de-
scriptions and repair instructions for the Volvo Penta
products or product versions noted in the table of con-
tents. Check that you have the correct Workshop
Manual for your engine.
Read the available safety information, ”General infor-
mation” and ”Repair instructions” in this workshop
manual before you start to do any service work.
Never do any work on an engine which just
hangs from a lifting device (crane etc.).
The engine must not be run in areas where ex-
plosive material or any gases are stored.
Only start the engine in a well-ventilated area. If
the engine is run in a confined space, make
sure that the crankcase ventilation and exhaust
gases can be led away from the workplace.
The battery lockers must never be exposed to
open flames or sparks. Never smoke close to
the batteries. The batteries generate hydrogen
gas when charged, which can form an explosive
gas when mixed with air. This gas mixture is
very flammable and highly explosive. A spark,
which can be caused by incorrect battery con-
nection, can cause a single spark which is suffi-
cient to cause an explosion with resulting dam-
age. Do not shift the connections when attempt-
ing to start the engine (spark risk) and do not
lean over any of the batteries. Please refer to
the advice in the instruction book.
Always ensure that the + (positive pole) and –
(negative pole) are securely connected to their
appropriate terminals on the battery. If the bat-
teries are wrongly connected, this can cause
severe damage to the electrical equipment.
Please refer to the wiring diagram.
Always use goggles when charging and han-
dling batteries. Battery electrolyte contains sul-
furic acid, which is highly corrosive. If battery
acid comes into contact with your skin, wash it
off at once with a lot of soap and water, and
then get medical help. If battery acid comes
into contact with your eyes, flush your eyes at
once (preferably with an eye shower) with a lot
of clean water, and then get medical help at
once.
Important!
The following special warning symbols occur in this
book and on the engine.
WARNING! Warns for the risk of personal injury,
property damage or that a mechanical fault can
occur if the instructions are not followed.
IMPORTANT! Is used to call attention to things
which could cause damage or malfunctions to
product or property.
NOTE! Is used to call attention to important informa-
tion, to facilitate work processes or operation.
Below is a summary of the risks involved and safety
precautions you should always observe or carry out
when performing work on the EMS 2 system.
Before electric welding is done, the connector
on the EMS system must be disconnected.
Disconnect the engine from system voltage by
turning off the main switch.
Disconnect the cable connectors from the con-
trol unit.
Reconnect the EMS 2 control module terminal
when the electric welding is finished and the elec-
tric welding equipment has been disconnected.
Be careful, watch out for the moving compo-
nents of the engine during function testing and
in operation. Approaching the engine during op-
eration entails a risk of personal injury. Remem-
ber that loose clothes or long hair can catch on
rotating components and cause severe injury.

4
General information
About this Workshop Manual
This workshop manual contains descriptions and re-
pair instructions for the standard versions of the
TAD734GE, TAD650VE, TAD660VE, TAD750 and
TAD760VE engines.
The workshop manual can illustrate tasks done on
any of the engines noted above. This means that the
illustrations and photographs which clarify certain de-
tails might not correspond with other engines in some
cases. Repair methods are similar in all important re-
spects, however. If this is not the case, this is noted.
Important differences are noted separately.
The engine designation and number are noted on the
number plate and engine decal. The engine designa-
tion and number must always be given in all corre-
spondence about any product.
The workshop manual is produced primarily for the
use of Volvo Penta workshops and service techni-
cians. For this reason the manual presupposes a cer-
tain basic knowledge and that the user can carry out
the mechanical/electrical work described to a general
standard of engineering competence.
Volvo Penta constantly improves its products, so we
reserve the right to make modifications without prior
notification. All information in this manual is based on
product data which was available up to the date on
which the manual was printed. Any material changes
introduced into the product or service methods after
this date are notified by means of Service Bulletins.
Spare parts
Spare parts for electrical and fuel systems are subject
to various national safety requirements. Volvo Penta
Original Spare Parts meet these specifications. Any
kind of damage whatsoever, occasioned by use of
non-original Volvo Penta spares for the product in
question, will not be compensated by the warranty of-
fered by Volvo Penta.
Certified engines
When doing service and repair on emission certi-
fied engines, it is important to be aware of the fol-
lowing:
Certification means that an engine type has been
checked and approved by the relevant authority. The
engine manufacturer guarantees that all engines made
of the same type are equivalent to the certified engine.
This makes special demands on service and repair
work, as follows:
●Maintenance and service intervals recommended
by Volvo Penta must be complied with.
●Only Volvo Penta original spares may be used.
●Service to injection pumps, pump settings and in-
jectors must always be done by an authorized
Volvo Penta workshop.
●The engine must not be converted or modified,
except for the accessories and service kits which
Volvo Penta has approved for the engine.
●No installation changes to the exhaust pipe and
engine air inlet ducts may be done.
●No seals may be broken by unauthorized personnel.
The general advice in the instruction book about oper-
ation, care and maintenance applies.
IMPORTANT! Delayed or inferior care/mainte-
nance, and the use of non-original spares parts
means that Volvo Penta can no longer be re-
sponsible for guaranteeing that the engine com-
plies with the certified version.
Damage and/or costs which arise from this will
not be compensated by Volvo Penta.
Group 30: Electrical system General information

Group 30: Electrical system Repair instructions
5
Repair instructions
The working methods described in the workshop man-
ual apply to work carried out in a workshop. For this
reason, the engine is lifted out and mounted on an en-
gine support. Unless otherwise stated reconditioning
work which can be carried out with the engine in place
follows the same working method.
The warning signs which occur in the workshop manual
(please refer to “Safety information” for their meanings).
WARNING!
IMPORTANT!
NOTE!
are not comprehensive in any way, since we can not of
course foresee everything, because service work is
done in highly varying circumstances. For this reason,
all we can do is to point out the risks which we believe
could occur due to incorrect work in a well-equipped
workshop, using work methods and tools tested by us.
All operations described in the Workshop Manual for
which there are Volvo Penta Special Tools available
assume that these tools are used when carrying out
the repair. Volvo Penta Special Tools have been de-
veloped to ensure the most safe and rational working
methods possible. It is therefore the responsibility of
anyone using other tools or other working methods
than we recommend to determine that there is no risk
of personal injury or mechanical damage or malfunc-
tion as a result.
In some cases special safety precautions and user in-
structions may be required in order to use the tools and
chemicals mentioned in the Workshop Manual. These
rules must always be observed, so there are no special
instructions about this in the workshop manual.
By following these basic recommendations and using
common sense it is possible to avoid most of the
risks involved in the work. A clean work place and a
clean engine will eliminate many risks of personal
injury and engine malfunction.
Above all, when work on fuel systems, lubrication
systems, inlet systems, turbocharger, bearing caps
and seals is done, it is extremely important that no
dirt or other kinds of foreign particles are able to get
in, since this would otherwise cause malfunctions or
shortened repair life.

Repair instructions Group 30: Electrical system
6
Our common responsibility
Each engine consists of a large number of collaborat-
ing systems and components. Any deviation of a com-
ponent from its technical specification can dramatical-
ly increase the environmental impact of an otherwise
good engine. For this reason, it is important that the
specified wear tolerances are observed, that systems
which are adjustable are correctly adjusted and that
Volvo Penta Original Spares are used for the engine.
The stated service intervals in the Maintenance
Schedule (see the Owner’s Manual) must be ob-
served.
Some systems, such as the components in the fuel
system, require special expertise and special testing
equipment for service and maintenance. For environ-
mental reasons etc., some components are sealed at
the factory. It is only permissible to work on sealed
components if you are authorized to do such work.
Remember that most chemical products, incorrectly
used, damage the environment. Volvo Penta recom-
mends the use of biodegradable degreasers whenever
engine components are de-greased, unless otherwise
specified in the workshop manual. When working
aboard a boat, be careful to ensure that oils, wash
residue etc. are processed for destruction, and are not
inadvertently discharged with bilge water into the envi-
ronment.
Tightening torques
The tightening torque for vital fasteners, which should
be tightened with a torque wrench, are listed in “Tech-
nical Data: Special tightening torques” and noted in the
job descriptions in the book. All torque specifications
apply to clean screws, screw heads and mating faces.
Torque data stated apply to lightly oiled or dry threads.
If lubricants, locking fluids or sealants are needed on a
fastener, the type of preparation to be used will be not-
ed in the job description and in “Tightening Torques”.
For fasteners where specific torque values are not giv-
en, please refer to “Technical data: General tightening
torques”. General torque specifications are target val-
ues and the fastener does not need to be tightened with
a torque wrench.
Dimension Torque
Nm
M5 ................................................. 6
M6 ................................................. 10
M8 ................................................. 25
M10 ............................................... 50
M12 ............................................... 80
M14 ............................................... 140
M16 ............................................... 220

7
Special tools
383 8619 VODIA complete diagnostic tool.*
Components:
3838620 VODIA – palmtop computer (PDA) with SD card.
3838621 VODIA – docking station. Used with VODIA PDA
(3838620).
3838622 VODIA – cable with connector. Used with dock-
ing station (3838621) on the engine’s communi-
cation connector.
*Note. More detailed information about using the VODIA tool can
be found in the tool’s instruction manual.
885675 Adapter cable for sensor test
9812519 Multimeter
999 9324 Terminal crimping tool
9998482 Gauge for connector on control unit
9998699 Measurebox
88890016 Adapter cable
885 675
383 8619
3838620 3838621 3838622
9812519
Special tools Group 30: Electrical system
888900169998699
9999324 9998482

EMS 2 - “Engine Management System” Group 30: Electrical system
8
EMS 2 - “Engine Management System”
General information
EMS 2 is an electronic system with CAN communication (Controller Area Network) for diesel engine control. The
system has been developed by Volvo and includes fuel control and diagnostic function.
The system consists of a control module, six injectors, a number of sensors that supply the control module with
measurements, sockets for diagnosis and functional checks. The engine can be connected to a communications
interface consisting of a CAN link and a serial link.
CAN - Controller Area Network
The J1939 CAN link is responsible after all communi-
cation between the engine control unit (EMS 2) and a
communication interface (such as CIU/DCU), except
for diagnostics. Diagnostics are managed by the so-
called J1708/J1587 link. The CAN link is much faster
than the J1708/J1587 link and has been designed to
connect to other components that support the SAE
J1939 protocol, such as instrument panels and trans-
missions.
If a fault develops on the CAN link, signals for the en-
gine speed potentiometer, and the start and stop
knobs are taken over by the J1708/J1587 link. Howev-
er, instrument and indicator lamps are completely
turned off.
If faults occur in both links, the engine starts to idle.
The only way to shut off the engine in this case is to
use the auxiliary stop (AUX-STOP).

Group 30: Electrical system EMS 2 - “Engine Management System”
9
DCU - Display Control Unit
DCU is a digital instrument panel that communicates
with the engine control module via the CAN link. DCU
has several functions, such as:
Engine control
– Start, stop, speed control, preheating etc.
Monitoring
– Engine speed, boost pressure, boost temperature,
coolant temperature, oil pressure, oil temperature,
engine hours, battery voltage, instantaneous fuel
consumption and fuel consumption (trip fuel).
Diagnostics
– Shows fault codes in text. Lists previous faults.
Parameter setting
– Idling speed, alarm limit for oil temperature/cool-
ant temperature, droop.
– Preheating for ignition.
Information
– Information about hardware, software and engine
identification.
CIU - Control Interface Unit
The CIU is a “translator” between the CAN bus and
the customer’s own control panel. This unit has two
serial communication links, one fast and one slow.
The fast one is a CAN link that features a bus speed
of 250 Kbit/s. All data regarding instruments, indicator
lamps, contacts and potentiometers are controlled by
this bus.
The slower J1708/J1587 link handles diagnostic infor-
mation for, among other things, the flashing code. The
VODIA diagnosis tool also uses the J1708/J1587 link
to communicate with the system.

EMS 2 - “Engine Management System” Group 30: Electrical system
10
Fuel control
The amount of fuel injected into the engine and the in-
jection advance are fully electronically controlled, via
fuel valves in the injectors, once the control unit has
analyzed the engine’s fuel requirements.
This means that the engine always receives the cor-
rect volume of fuel in all operating conditions, which
offers lower fuel consumption, minimal exhaust emis-
sions etc.
The control unit monitors and reads the injectors to
ensure that the correct volume of fuel is injected into
each cylinder, and it calculates and set the injection
advance. Control is mainly done with the help of the
speed sensors, fuel pressure sensor and the com-
bined sensor for boost pressure/boost temperature.
The control unit controls the injectors via a signal to
the electromagnetically operated fuel valve in each in-
jector, which can be opened and closed.
Calculation of fuel quantity
The quantity of fuel to be injected into the cylinder is
calculated by the control unit. The calculation deter-
mines the time that the fuel valve is open (when the
fuel valve is open fuel is sprayed into the cylinder).
The parameters which govern the amount of fuel in-
jected are:
• Demanded engine speed
• Engine protector functions
• Temperature
• Boost pressure
Altitude correction
The control unit contains an atmospheric pressure
sensor and an altitude compensation function for en-
gines that operate at high altitude. This function limits
the fuel volume in relation to ambient air pressure.
This is to prevent smoke, high exhaust temperature
and to protect the turbocharger from overspeeding.
Diagnostic function
The task of the diagnostic function is to discover and
localize any malfunctions in the EMS 2 system, to
protect the engine and to inform about any problems
that occur.
If a malfunction is discovered, this is announced by
warning lamps, a flashing diagnostic lamp or in plain lan-
guage on the instrument panel, depending on the equip-
ment used. If a fault code is obtained as a flashing code
or in plain language, this is used for guidance in any fault
tracing. Fault codes can also be read by Volvo’s VODIA
tool at authorized Volvo Penta workshops.
In case of serious disturbances, the engine is shut
down completely or the control module decreases the
power output (depending on the application). Once
again, a fault code is set for guidance in any fault
tracing.

Group 30: Electrical system Component location
11
Component location TAD 650, 660, 750, 760 VE
NOTE! Location can differ, depending on engine model.
1. Speed sensor, camshaft
2. Connection, EMS 2
3. Solenoid controlled proportional valve, high pres-
sure pump – fuel (MPROP)
4. Fuel pressure
5. Fuel pressure in comman rail
6. Glow plugs, one for each injector
7. Oil pressure sensor
8. Boost pressure and temperature
9. Solenoid valve, EGR
10. Coolant temperature
11. Speed sensor, crankshaft
12. Water in fuel (not shown, mounted on primary
fuel filter).
1
2
3456
7
8
9
10
11

Component description Group 30: Electrical system
12
Component location TAD 734 GE
1. Solenoid controlled proportional valve,
high pressure pump – fuel (MPROP)
2. Coolant temperature sensor
3. Water in fuel switch(mounted on primary
fuel filter).
4. Boost pressure and temperature sensor
5. Preheater, intake manifold
6. Fuel pressure in comman rail
7. Fuel pressure sensor
8. Oil pressure sensor
9. Main relay
10. Speed sensor, crankshaft
11. Speed sensor, camshaft

Group 30: Electrical system Component description
13
Starter motor
The starter motor is installed in the flywheel housing,
on the left-hand side of the engine. The starter motor
relay is “positive connected”, which means that the re-
lay is connected to battery voltage.
Alternator
The alternator is belt driven and mounted on the front
of the engine, on the right.
Component description

Component description Group 30: Electrical system
14
Injectors
The injectors are installed on the cylinder head.
The amount of fuel injected and injection duration is
controlled by the engine control unit, via electromag-
netically controlled fuel valves in the injectors. This
means that the engine always receives the correct
volume of fuel in all operating conditions, which offers
lower fuel consumption, minimal exhaust emissions
etc.
Speed sensor, crankshaft
The engine speed sensor is an inductive sensor.
When the crankshaft rotates impulses are created in
the sensor via a tooth wheel on or behind the torsion
damper. The impulses create a pulse signal in the
sensor that the engine control unit (EMS 2) uses to
calculate the crankshaft’s rpm.
The tooth wheel has a tooth free gap for the EMS 2 to
recognize the crankshafts position.
The signal is sent to the engine control unit, which
calculates the injection in advance and the amount of
fuel to be injected.
Speed sensor, camshaft (cam-
shaft position)
The camshaft sensor is an inductive sensor. When
the camshaft rotates impulses are created in the sen-
sor via a tooth wheel installed on the camshaft. The
tooth has seven teeth, one for each cylinder and one
to determine when cylinder one is to be injected. The
impulses create a pulse signal in the sensor that the
engine control unit (EMS 2) uses to calculate when a
cylinder is in turn for injection.

Group 30: Electrical system Component description
15
Sensor, boost pressure/ boost
temperature
The boost pressure and the boost temperature are
measured by a combined sensor located on the inlet
manifold on the left of the engine.
The sensor is supplied by a 5 Volt reference voltage
from the engine control module.
The boost pressure sensor measures the absolute
pressure, which is the sum of the boost pressure and
atmospheric pressure (300 kPa thus corresponds to a
boost pressure of 200 kPa when atmospheric pres-
sure is 100 kPa).
The pressure signal is a voltage signal which is pro-
portional to absolute pressure.
The boost temperature sensor consists of a non-lin-
ear resistor, whose resistance varies with boost tem-
perature. The resistance falls as the temperature ris-
es.
Sensor, oil pressure, engine
Oil pressure is measured by a sensor installed in the
engine block on the right side of the engine.
The sensor measures pressure in the main oil gallery,
and is supplied by a 5 Volt reference voltage from the
engine control module.
The pressure signal is a voltage signal which is pro-
portional to the lubrication oil pressure.
IEGR (only VE engines)
The IEGR valve is a 2-way solenoid valve controlled by
the engine control unit. The IEGR solenoid controls a
oil pressure that effects a control valve which activate
the exhaust gas recirculation function.

Component description Group 30: Electrical system
16
Sensor, fuel pressure
The sensor measures fuel pressure and is located on
the fuel filter bracket. The sensor is an active sensor,
i.e. the sensor requires a supply voltage of +5 Volt.
The sensor provides an output signal whose voltage is
proportional to the pressure that the sensor measures.
Coolant temperature sensor
The sensor is located on the cylinder head, at the rear
end of the engine.
The sensor senses the engine coolant temperature
and sends the information to the engine control unit.
The sensor consists of a non-linear resistor, whose re-
sistance varies with coolant temperature. The resis-
tance falls as the coolant temperature rises.
Sensor, common rail pressure
(fuel)
The sensor is mounted on the right of the engine, at
the front of the common rail, which distributes fuel to
the injectors.
The rail pressure sensor senses the fuel pressure and
converts this to a voltage which is registered by the
engine control unit.

Group 30: Electrical system Component description
17
Magnetically controlled propor-
tional valve (MPROP)
A magnetically controlled proportional valve (MPROP)
controls the high pressure pump to ensure that the
correct fuel pressure (rail pressure) is retained despite
varying engine speed and loading.
The input signal to the valve is a PWM signal whose
pulse width is controlled by the engine control module.
When the current through the valve is changed, this af-
fects the fuel flow, which results in changed rail pres-
sure.
Water in fuel switch, secondary
fuel filter
A switch is located in the water trap under the fuel fil-
ter. Its task is to detect whether there is water in the
fuel.
The switch senses the resistance between two pins,
wich are in contact with the fuel. When there is no wa-
ter in the fuel, the resistance is very high. If there is
any water in the fuel, the resistance falls.
Switch, coolant level
The task of the switch is to discover whether the cool-
ant level in the engine (expansion tank) has become
too low. An alarm signal is sent when the coolant level
is too low.

Component description Group 30: Electrical system
18
Engine control unit, EMS 2
The engine control unit checks and controls the injec-
tors, to ensure that the correct volume of fuel is inject-
ed into each cylinder at the right time. It also controls
the high pressure pump via the proportional valve
(MPROP) to ensure that the system always has the
correct fuel pressure (rail pressure).
The control unit also calculates and adjusts the injec-
tion advance. Regulation is mainly done with the aid of
the engine speed sensor and the combined sensor for
boost pressure/boost temperature.
The EMS 2 system processor is located in the control
unit, protected from water and vibration.
The processor receives continuous information about:
•Engine speed
•Throttle
•Oil pressure
•Boost pressure / temperature
•Fuel pressure (common rail pressure)
•Fuel alarm, “water in fuel”
•Camshaft position
•Coolant temperature
The information provides information about current op-
eration conditions and allows the processor to calculate
the correct fuel volume, monitor engine status etc.
Preheater with preheater relay
The preheater is located in the inlet manifold at the left
side of the engine. The preheat relay is located at the
engines left side beneath the preheater.