Engine Control Module: Description and Operation

GF07.16-S-6000SA Component Description For CDI Control Unit

ENGINES 642.8 in MODEL 906
- with CODE (MG5) Engine OM 642 DE 30 LA, 140 kW (190 hp) 3800 rpm
- except CODE (ZU7) National version for Canada
- except CODE (ZU8) National version for USA

ENGINES 642.8 in MODEL 639
- with CODE (XZ1)
- with CODE (MZ0) Blue EFFICIENCY

Illustrated on model 906






N3/30 CDI control unit

Location
The CDI control unit is located at the front left in the engine compartment.

Task
The CDI control unit operates in an electrical network of sensors and actuators to form the engine control system for engine 642.8.
The following systems and functions are controlled and coordinated by the CDI control unit according to input signals:
- Fuel supply
- Glow system control
- Injection quantity control
- Diagnosis and fault storage
- Engine timing start-stop function (for code (MJ7) ECO start/stop function (for model 639) or for code (MJ7) ECO Start (for model 906))
- Drive authorization system and immobilizer
- Heat management
- Torque interface
- Alternator interface
- Exhaust gas recirculation
- Emission control

The CDI control unit has an internal atmospheric pressure sensor.

Input and output signals
The following input signals are evaluated by the engine control system and respective output signals are issued:
- Direct input signals
- Direct output signals
- LIN signals
- CAN input signals
- CAN output signals

Direct input signals
- Terminal 15
- Terminal 30
- Terminal 87
- Hot film mass air flow sensor (B2/14)
- Rail pressure sensor (B4/17)
- Boost pressure sensor (B5/8)
- Camshaft sensor (B6/24)
- Coolant temperature sensor (B11/19)
- Temperature sensor upstream of turbocharger (B16/11)
- Charge air temperature sensor (B17/15)
- Temperature sensor upstream of diesel particulate filter (B19/19)
- Exhaust gas recirculation cooler temperature sensor (B19/21) (for model 639) or exhaust gas recirculation cooler temperature sensor (B19/15) (for model 906)
- Intake manifold pressure sensor (B28/19)
- Diesel particulate filter differential pressure sensor (B28/20)
- Accelerator pedal module (B37/4) (for model 639) or accelerator pedal module (B37/3) (for model 906)
- Engine oil sensor (B40/8)
- Fuel temperature sensor (B50/6)
- Exhaust back pressure sensor (B60/4)
- Crankshaft sensor (B70/1)
- Fuel filter heater with water level sensor (R53/1)
- Oxygen sensor (B85/3)
- Intake port shutoff positioner (M72/2)

Direct output signals
- Accelerator pedal sensor
- Fuel filter heater with water level sensor
- Oxygen sensor
- Tml. 15 relay (K40/9k8)
- Engine circuit 87 relay (K40/9k4) (for model 639) or engine timing circuit 87 relay (K40/9k7) (for model 906)
- Throttle valve actuator (M16/48)
- Inlet port shutoff positioner
- Electronically regulated fuel pump (N118) (for model 639) or FSCU (N118/5) (for model 906)
- Vent line heater element (R39/4)
- Exhaust gas recirculation cooling switchover valve without SRA (Y27/2) (for model 639)
- Exhaust gas recirculation cooling switchover valve with SRA (Y27/3) (for model 639)
- Exhaust gas recirculation cooling switchover valve (Y27/13) (for model 906)
- Exhaust gas recirculation positioner (Y27/17)
- Pressure regulating valve (Y74/6)
- Cylinder 1 injector (Y76/18)
- Cylinder 2 injector (Y76/19)
- Cylinder 3 injector (Y76/20)
- Cylinder 4 injector (Y76/21)
- Cylinder 5 injector (Y76/22)
- Cylinder 6 injector (Y76/23)
- Boost pressure positioner (Y77/8)
- Quantity control valve (Y94/4)

LIN signals
- Alternator interface via drive LIN (LIN C1)
- Alternator (G2/6) (for model 639) or alternator with LIN bus (G2/7) (for model 906)
- Glow output stage (N14/7), to control various glow functions and send system errors

CAN input signals

Instrument cluster (A1)
- Fuel reserve signal

Lowline airbag control unit (N2/14)
- Crash signal

ETC [EGS] control unit (N15/3)
- Gear selection

ESM [EWM] control unit (N15/5)
- Selector lever module position

ESP control unit (N30/4)
- Vehicle speed
- Wheel speed signal
- Brake recognition
- Cruise control request
- Engine torque request

EZS control unit (N73)
- Start enable (drive authorization system)

Electronically regulated fuel pump (for model 639)
- Self-diagnosis data
- Requested diagnostic data

CAN output signals

Instrument cluster
- Fuel consumption (the trip computer is informed about the current fuel consumption by means of square-wave pulse packages (1 pulse = 0.2 l/h))
- Engine oil level too low
- Circuit 61 signal (generated by CDI control unit)

EZS control unit
- Start enable request (drive authorization system)

Electronically regulated fuel pump (for model 639) or FSCU (for model 906)
- Diagnosis request

Design
The housing of the CDI control unit is made of die-cast aluminum and the cover is made of corrosion-proof sheet steel. The CDI control unit is water proof and dust proof.
The housing contains the 32-bit measuring and control electronics for the engine control.

Power supply
The CDI control unit is supplied with power by "circuit 30 fused" and, with the ignition on, by "circuit 87". In the operating voltage range it has both short-circuit protection and reversed polarity protection. Power is supplied through several pins connected in parallel to relieve the electrical connectors.

Ground connection
The ground connection "terminal 31" takes place over a number of ground lines to the lamp unit ground point at the front right (W2) (for a left-hand drive vehicle) or the lamp unit ground point at the front left (W9) (for RHD in model 639) or lamp unit ground point at the front left (W9/6) (for model 906).

Processor run-on
When the CDI control unit receives the signal "circuit 15 OFF", a processor run-on of approx. 4 seconds is started.
However, it may also last for several minutes due to various functions (for example, on-board diagnosis (OBD), drive authorization system (DAS), thermal management).

Assembly operations
Ensure before unplugging the plug on the CDI control unit that the ignition is switched off and processor run-on has ended.

This is to prevent damage to the CDI control unit and save errors in the control units linked to the CAN.

Variants
The engine control variants (e.g. national and exhaust variants) are activated with X entry Diagnostics using the variant coding function. Replacement of the CDI control unit is not necessary.