Coolant connection
EGR cooler
Cylinder Head Coolant Valve N489 (mounted on
water pump)

10
11
12
13
14
15
16
17
18

Coolant thermostat
Throttle valve
Engine oil cooler
Coolant Fan V7
Coolant Fan 2 V177
Radiator
Charge Air Cooling Pump V188
Charge air cooler integrated in intake manifold
Heat exchanger for charge air cooling
Cooled coolant
Heated coolant

36

Coolant thermostat
The coolant thermostat (3/2-way valve) is activated by an
expanding wax element, which begins to close the secondary cooling circuit when operating temperature is reached.
The primary cooling circuit is closed at the same time.

Secondary cooling circuit (micro circuit)

Connection to main
radiator closed

from
cylinder block

By-pass (short circuit) to
coolant pump open

608_005

Primary cooling circuit (high temperature circuit, controlled)

Connection to main
radiator open

from
cylinder block

By-pass (short circuit) to
coolant pump closed
608_006
37

Coolant expansion tank with silicate repository
There is a silicate repository in the coolant expansion tank.
The silicate is used to protect the aluminium components
in the coolant circuit from corrosion. The silicates in the
coolant G13 dissipate over time if the engine is subject to
high thermal loads.

To compensate for the silicate consumption, silicate is
taken from the repository and added to the coolant. The
silicate repository is therefore used as additional protection
against corrosion for aluminium components in the coolant
circuit over the entire lifespan of the engine. The silicate
repository is not a serviceable item and it is designed to
last for the life of the vehicle.

Engine Coolant Level Sensor G32

Coolant expansion tank

Coolant return

Silicate container

Silicate

Coolant supply

s514_079

38

Fuel System
4
6

9

7

8

10
5
11

12

12

12

12

1
3

2

Key:
Fuel high pressure maximum 1800 bar
Fuel return 0 - 1.0 bar

s514_027

Fuel supply pressure 3.5 - 5.0 bar as required
Fuel return pressure from the injectors 0.4 - 1.0 bar

1 - Fuel Pump Control Module J538
J538 controls the pressure in the fuel supply and monitors the
function of the fuel pump as required.

7 - Fuel Pressure Regulator Valve N276
N276 is used to adjust the fuel pressure in the high-pressure
range.

2 - Transfer Fuel Pump G6
G6 generates the fuel pressure in the fuel supply.

8 - High-Pressure Accumulator (rail)
The high-pressure accumulator stores the fuel required for
injection into all cylinders under high pressure.

3 - Fuel Filter
The fuel filter keeps impurities in the diesel fuel from the
components of the injection system. The high precision components, for example, the high-pressure pump and the injectors,
can be damaged or their function impaired by even the most
minute particles of dirt.

9 - Fuel Pressure Sensor G247
G247 measures the current fuel pressure in the high-pressure
area.

4 - Fuel Temperature Sensor G81
G81 measures the current fuel temperature.

10 - Pressure Retention Valve
The pressure retention valve ensures a constant pressure of
about 1 bar in the return of the injectors. This avoids variations
in pressure and allows precise control of the injectors.

5 - High-Pressure Pump
The high-pressure pump generates the high fuel pressure
required for injection.

11 - Pulsation Damper
The pulsation damper has the task of reducing distracting
noises caused by pulsating fuel in the fuel return line.

6 - Fuel Metering Valve N290
N290 regulates the quantity of fuel needed to generate the
high pressure as required.

12 - Injectors N30, N31, N32, N33
The injectors inject the fuel into the combustion chambers.

39

Fuel injectors
The fuel injectors are controlled by a solenoid valve actuator.
Bosch has developed an injector with solenoid valve technology that fulfils the requirements for high injection
pressures and the ability to perform several injections per
work cycle. Solenoid valve-controlled injectors have the
advantage that they are simpler to manufacture than
injectors with a piezo actuator.

Injector

Clamping piece

Clamping piece

s514_029

40

Injector in rest position
Design
In its rest position, the injector is closed. The solenoid is
not actuated. The solenoid valve armature is pushed into its
seat by the force of the solenoid valve spring and thus
closes the path from the valve control chamber to the fuel
return. The fuel is under high pressure in the valve control

chamber. Due to the larger pressure/surface ratio of the
control piston surface to the injector needle, the injector
needle is pushed into its seat and closes the injection
nozzle.

Fuel return

High-pressure fuel connection

Valve control chamber

Spring
Solenoid

Armature
Stay bolt
Outflow choke

Valve control chamber
Control piston

Inflow choke
Injector needle

s514_049

Key:
High pressure
Return pressure

41

Start of injection
The solenoid is activated by the ECM to initiate the injection
cycle. As soon as the magnetic force exceeds the closing
force of the solenoid valve spring, the solenoid valve armature moves upwards, opening the outflow choke. The fuel in
the valve control chamber flows via the opened outflow

choke into the fuel return line. The fuel pressure in the
valve control chamber falls. The inflow choke prevents rapid
pressure equalization between the fuel high-pressure
section and the valve control chamber. The injector needle
is raised by the high fuel pressure and injection begins

Fuel return

High-pressure fuel connection

Valve control chamber

Spring
Solenoid

Armature
Stay bolt
Outflow choke

Valve control chamber
Control piston

Inflow choke
Injector needle

s514_050

Key:
High pressure
Return pressure

42

Pre-heating the fuel filter
When the fuel temperature is cold, warmed fuel from the
high-pressure accumulator (rail) is directed into the supply
line upstream of the fuel filter. This prevents the fuel filter
becoming clogged with crystallized paraffins.

To allow the fuel to be warmed quickly when the engine is
cold, Fuel Metering Valve N290 supplies more fuel than is
required for injection to the pressure chamber of the
high-pressure pump. The fuel warmed during pressurization is sent from the high-pressure accumulator (rail) via
Fuel Pressure Regulator Valve N276 into the fuel filter
return line.

2
5

3

6

4

1

s514_108

Key:

1

Fuel filter

4

High-pressure pump

2

Fuel Temperature Sensor G81

5

High-pressure accumulator (rail)

3

Fuel Metering Valve N290

6

Fuel Pressure Regulator Valve N276

43

Pulsation damper
A pulsation damper is integrated near the plenum chamber
bulkhead in the fuel return line. It has the task of reducing
distracting noises caused by pulsating fuel in the fuel
return line.
To reduce the pulsation in the fuel return line, a cushion of
air builds up in the pulsation damper when the engine is
running. The air cushion absorbs the pressure pulsations in
the fuel return line and thereby reduces the vibrations.

s514_052a

Pulsation damper

Pulsation damper

Air cusion

Pulsation damper

1

Air cusion

2
Fuel return

Fuel return

s514_057

s514_058

44

Engine management system
System overview
Sensors
Mass Airflow Sensor G70
Throttle Position Sensor G69
Engine Speed Sensor G28
Hall Sensor G40
Engine Coolant Temperature Sensor G62
Fuel Temperature Sensor G81

NOx Sensor Control
Module J583

Engine Coolant Temperature Sensor on Radiator Outlet G83
Oil Level Thermal Sensor G266
Fuel Pressure Sensor G247

NOx Sensor G295

Accelerator Pedal Position Sensor G79 and
Accelerator Pedal Position Sensor 2 G185
Exhaust Gas Recirculation Position Sensor 2 G466
Charge Pressure Actuator Position Sensor G581

NOx Sensor Control Module 2
J881

Brake Light Switch F
Brake Pedal Switch F63

NOx Sensor 2 G687
Heated Oxygen Sensor G39
Charge Air Temperature Sensor in front of Charge Air Cooler G810
Charge Air Temperature Sensor after Charger Air Cooler G811

Charge Pressure Actuator Position Sensor G581

Oil Pressure Switch F22
Reduced Oil Pressure Switch F378

Engine Control
Module J623

Exhaust Gas Temperature Sensor 3 G495

EGR Temperature Sensor G98
Data Link Connector
Exhaust gas Temperature Sender 1 G235
Exhaust Gas Temperature Sensor 4 G648
Charge Air Pressure Sensor G31
Differential Pressure Sensor G505
Auxiliary signals:
−− Cruise control system
−− Speed signal
−− Start request to ECM (Kessy 1 + 2)
−− Terminal 50
−− Crash signal from Airbag Control Module

45

Private CAN bus

Combustion Chamber Pressure Sensors G677 - G680

Actuators
Injectors, cylinders 1 – 4
N30, N31, N32, N33

Automatic Glow Time Control Module J179
Glow plugs 1 – 4 Q10, Q11, Q12, Q13

Oil Pressure Regulation Valve N428

Throttle Valve Control Module J338

Fuel Metering Valve N290

Fuel Pressure Regulator Valve N276
EGR Motor V338
(Low pressure exhaust gas recirculation)
EGR Motor 2 V339
(High pressure exhaust gas recirculation)

EGR Cooler Switch Over Valve N345
(EU4)

Cylinder Head Coolant Valve N489

Charge Air Cooling Pump V188

Wastegate Bypass Regulator Valve N75

Heater Support Pump V488

Exhaust Door Control Unit J883

Positive Crankcase Ventilation Heating Element N79
(cold-climate countries only)
Fuel Pump Control Module J538

Oxygen Sensor Heater Z19
Reducing Agent Metering System Control Module J880
Reducing Agent Injector N474
Reducing Agent Line Heater (heating circuit 2) Z104
Reducing Agent Pump V437
Reducing Agent Tank Heater (heating circuit 1) Z102
Fuel Pump Relay J17
Transfer Pump G6
Auxiliary signals:
−−
A/C compressor
−−
Auxiliary coolant heater
−−
Fan setting 1 + 2
−−
Auxiliary air heater element Z35

608_058
46

Glow plug system
The EA288 engine for the North American market uses a
rapid start glow plug system. The advantages of this
system are:
•

Engine start comparable to a gasoline engines at
temperatures down to -24 °C

•

Extremely short heating time. Within 2 seconds, the
glow plug temperatures reach up to 1000 °C

•

Controllable temperatures for preglow and afterglow
phases

•

Self-diagnostic ability

Overview of the system

Engine Control
Module J623

Glow plug 1 Q10

Engine Speed
Sensor G28

Automatic Glow Time
Control Module J179

Glow plug 2 Q10

Engine Coolant
Temperature Sensor
G62
Data Bus Onboard
Diagnostic Interface
J533

Glow plug 3 Q10

Vehicle Electrical System
Control Module 1 J519

Glow plug 4 Q10
Instrument Cluster
Control Module
J285

Glow period warning
lamp K29

s514_081

Pressure Sensing Glow Plugs

47

Function
Pre-glowing
For rapid starting at an exterior temperature of less than
24 °C, there is a maximum of 11.5V. This ensures the glow
plug is heated to over 1000 °C within a short period of time
(approximately 2 seconds). This reduces the pre-glow time
for starting.

Engine Control Module J623 determines when to activate
the steel glow plugs via Automatic Glow Time Control
Module J179. J179 uses a PWM signal to activate the
plugs. The voltage of the individual glow plug is adjusted
via the duty cycle.

Post-start glowing
For post-start glowing, the switch-on time of the supply
voltage is adjusted in the PWM duty cycle to ensure that
there is an effective voltage of 4.4 V. Post-start glowing is
carried out for a maximum of 5 minutes after starting the
engine up to a coolant temperature of 24 °C. Post-start
glowing helps reduce hydrocarbon emissions and combustion noises during the warm-up phase.

On vehicles with a start/stop system, the post-start
glowing process is not interrupted if the engine-stop function is active. This avoids frequent temperature changes
and protects the material of the steel glow plug.

Phase-shifted activation of the glow plugs
Glow plug

To relieve the load on the supply voltage during the glow
phases, the glow plugs are actuated in a phase-shifted
manner. The falling signal actuates the next glow plug.

Cylinder 1
Cylinder 2
Cylinder 3
Cylinder 4