The CDI control unit (N3/9) reads in the signals from the following components:
Hot film mass air flow sensor (B2/5), with Code (MF4)
low-emission engine as per EU4 Group 3
Rail pressure sensor (B4/6)
Boost pressure sensor (B5/1)
Camshaft Hall sensor (B6/1)
Coolant temperature sensor (B11/4)
Charge air temperature sensor (B17/9)
Pressure sensor downstream of air filter (B28/5)
Pedal value sensor (B37/3)
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Oil sensor (oil level, temperature and quality) (B40)
Fuel temperature sensor (B50)
Fuel filter water level sensor (B76), with Code (KL5) Fuel filter with water separator
O2 sensor upstream TWC [KAT] (G3/2), with Code (MF4)
low-emission engine as per EU4 Group 3
Crankshaft position sensor (L5)
Clutch pedal switch (S40/3), with transmission 716.6
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The CDI control unit (N3/9) actuates the following components:
Starter relay (K40/9k5)
Fuel pump relay (K40/9k6)
Common rail high pressure pump (M41)
Glow output stage (N14/2)
Vent line heater element (R39/1)
Exhaust gas recirculation positioner (Y27), with Code (MF8) Low-emission engine as per EU3 Group 3 or with Code (MF4) Low-emission engine as per EU4 Group 3
Boost pressure control transducer (Y31/5)
Pressure control valve (Y74)
Fuel injector, cylinder 1 (Y76y1)
Fuel injector, cylinder 2 (Y76y2)
Fuel injector, cylinder 3 (Y76y3)
Fuel injector, cylinder 4 (Y76y4)
Inlet port shutoff switchover valve (Y83), with Code (MF4) Low-emission engine as per EU4 Group 3
Quantity control valve (Y94)
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The CDI control unit (N3/9) communicates with the following control units via the Controller Area Network bus Class C (engine compartment) (CAN C):
Instrument cluster (A1)
SRS control unit (N2/10)
ETC [EGS] control unit (N15/3), with transmission 722.6
Electronic selector lever module control unit (N15/5) with transmission 722.6
ESP control unit (N30/4)
EIS [EZS] control unit (N73)
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The CDI control unit (N3/9) controls the following systems according to the evaluation of input signals:
Fuel supply
Control of the glow system during engine start and in driving mode
Fuel injection quantity control during engine start and in driving mode
Emission control system
Boost pressure control
Shutoff of the refrigerant compressor (A9), with Code (HH4) Automatic air conditioning or with Code (HH9) 'Tempmatic' regulated air conditioning
Shutoff control
European on-board diagnosis (EOBD)
Diagnosis/DTC memory
The CDI control unit (N3/9) checks its inputs and outputs for plausibility and recognizes possible faults. The following faults can be distinguished:
Hard faults, namely: Continuous faults can only be read out and deleted using STAR DIAGNOSIS.
Sporadic faults, namely: Faults that occur intermittently (such as loose contact) while driving are deleted after a change in status in circuit 30 in the CDI control unit (N3/9).