Notes on fault memory
All inputs/outputs are checked for plausibility during operation.
All faults which exist for more than 0.5 s are stored in the fault memory of the DFI control module (N3/8)
The faults remain stored with ignition "OFF" and after disconnecting the vehicle battery.
In the case of major faults which exist for > 1 s, the Electronic Diesel Control malfunction indicator lamp (EDC, A1e34) is illuminated.
Such faults are:
- CKP sensor (IFI/DFI) (L5/6)
- Distributor pump (DFI) (Y23/2)
- Cam ring position sensor (Y23/2l1)
- Distributor shaft position sensor (Y23/2l2)
- Shut-off valve (Y23/2y1)
- Check valve (Y23/2y2)
- Adjusting valve (Y23/2y3)
- Supply valve (Y23/2y4)
- IFI/DFI accelerator pedal position sensor (R25/2).
Fault ambient data
The fault ambient data at the time the fault was
stored can also be displayed with the HHT. The display screens are contained in menu item "2 stored faults" 1st display screen
2nd display screen
The following faults are automatically erased by the DFI control module (N3/8), as soon as they are no longer present
(e. g. loose contact rectified), but are retained in the fault memory:
- Pressure sensor (B28)
- IAT sensor (B17)
- Coolant temperature sensor (B11/4)
- Fuel temperature sensor (Y23/2b1)
- Stop lamp switch (S9/1)
- Starter lock-out/backup lamp switch (S16/1, AT only)
- Electronic intake port shutoff vacuum transducer (Y31/7)
- EGR switchover valve (Y27)
- Pressure control flap switchover valve (Y28)
- Modulator pressure switchover valve (AT/CC) (Y3/4)
- Upshift delay switchover valve (AT/CC) (Y3/5)
Formation of substitute value in the event of signal failure
In the event of a failure of input signals the DFI control module (N3/8) forms a substitute value on the basis of other signals in order to retain system operation.
Formation of a substitute value may result in:
- Reduction in engine output/reduction in maximum engine speed
- Deactivation of smooth running control
- Failure of exhaust gas recirculation
- Failure of Cruise control (AT only)