Component description for CDI control unit

D07.08-1107-08

Location

N3/21 CDI control unit

The CDI control unit is on the left in the engine compartment.

Task

The CDI control unit controls the following systems depending on the information received:

- Fuel supply

- Control of the glow system at engine start and when driving

- Control of the quantity of fuel injected at engine start and when driving

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- Emission control system

- Boost pressure control

- Shutoff of refrigerant compressor (A9), with code (HH9) Regulated air conditioning, (Tempmatic) and with code (HH7) Additional air conditioning system in rear, or shutoff of 2nd refrigerant compressor (A9/7), with code (H08) High-performance air conditioning system

- Shutoff control

- European on-board diagnosis (EOBD)

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The CDI control unit reads the signals from the following components:

- Engine oil sensor (B40/5)

- Rail pressure sensor (B4/6)

- Boost pressure sensor (B5/1)

- Camshaft sensor (B6/19)

- Coolant temperature sensor (B11)

- Charge air temperature sensor (B17/9)

- Intake manifold pressure sensor (B28)

- Accelerator pedal module (B37/3)

- Fuel temperature sensor (B50)

- Fuel filter water level sensor (B76), with code (KL5) Fuel filter with water separator

- Crankshaft sensor (L5/7)

- Engine start/stop switch (S2/6), with code (MJ7) ECO start

- Clutch pedal switch (S40/3), with transmission 711.6

- Clutch pedal switch (S40/6), with transmission 711.6

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- Engine hood switch (S62/41), except code (FZ5) Anti-theft alarm system (ATA), except code (FZ4) Anti-theft alarm system with interior protection and tow-away protection or except code (FY1) ATA 2 with interior protection, tow-away protection and battery-operated horn and with code (MJ7) ECO start

- Transmission neutral position switch (S164), with transmission 711.6

On vehicles with code (MF4) Low-emission engine conforming to EU4 group 3 or with code (MS9) Engine version Euro 4, signals from the following components are additionally read in:

- Hot film mass air flow sensor (B2/5)

- Intake air temperature sensor (B2/5b1)

- Catalytic converter temperature sensor (B19)

- Temperature sensor upstream of diesel particulate filter (B19/12)

- Diesel particulate filter differential pressure sensor (B28/8)

- Exhaust back pressure sensor (B60)

- Oxygen sensor (B85)

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In addition, the following sensor is installed in the CDI control unit:

- Internal atmospheric pressure sensor for altitude adaptation

The CDI control unit actuates the following components:

- Fuel pump relay (K40/9k3)

- Circuit 50 starter relay (K40/9k5)

- Throttle valve actuator (M16/40)

- High-pressure pump (M41)

- Vent line heater element (R39/1)

- Exhaust gas recirculation positioner (Y27/11), with code (MF4) Low-emission engine conforming to EU4 group 3 or with code (MS9) Engine version Euro 4

- Boost pressure control pressure transducer (Y31/14), with code (MS9) Engine version Euro 4

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- Pressure regulator valve (Y74)

- Cylinder 1 injector (Y76/1)

- Cylinder 2 injector (Y76/2)

- Cylinder 3 injector (Y76/3)

- Cylinder 4 injector (Y76/4)

- Wastegate pressure transducer (Y77), with code (MS9) Engine version Euro 4

- Boost pressure positioner (Y77/1), with code (MS9) Engine version Euro 4 or with code (MF4) Low-emission engine conforming to EU4 group 3

- Intake port shutoff switchover valve (Y83) with integrated intake port shutoff positioner (M72), with code (MF4) Low-emission engine conforming to EU4 group 3

- Quantity control valve (Y94)

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Communication via the Local Interconnect Network (LIN) takes place via the following components:

- Alternator (G2/7)

- Glow output stage (N14/2), control of various glow functions and transmission of system errors

The CDI control unit communicates with the following components via the Controller Area Network bus Class C (engine compartment) (CAN C):

- Instrument cluster (A1), actuation of preglow indicator lamp (A1e13), actuation of EOBD indicator lamp (A1e17)

- Lowline airbag control unit (N2/14), except code (SH6) Thoraxbag for driver (in backrest), except code (SH7) Thoraxbag for driver and front passenger (in backrest) or except code (SH9) Windowbag for driver and front passenger

- Highline airbag control unit (N2/15), with code (SH6) Thoraxbag for driver (in backrest), with code (SH7) Thoraxbag for driver and front passenger (in backrest) or with code (SH9) Windowbag for driver and front passenger

- ETC [EGS] control unit (N15/3), with transmission 722.6

- ESM [EWM] control unit (N15/5), with transmission 722.6

- ESP control unit (N30/4)

- EIS [EZS] control unit (N73)

- SCM [MRM] control unit (N80)

 The CDI control unit is equipped with a fault memory, which can be read out via STAR DIAGNOSIS.