Trip computer (TRIP) explanations on diagnosis troubleshooting chart - AD54.50-P-5000-01GH

Explanatory notes on diagnosis 

The trip computer receives all necessary external information via CAN lines. It is therefore not possible to check the corresponding input signals directly. To limit any faults it is therefore important to pay attention also to faults in other systems and in particular to implausible displays in the instrument cluster (A1). If, for example, the vehicle speed is not displayed correctly on the instrument cluster (A1), the traction system control module (N47) may be defective and not giving the wheel speeds correctly to the CAN data buses. As a result the "fuel consumption" and "range" functions of the trip computer cannot be displayed correctly. In this case it is useful to read out the corresponding actual values (wheel speeds) of the instrument cluster (A1) or traction system control module (N47) with the HHT.

If the fuel consumption displays are faulty, the fuel consumption signal may also be faulty. The actual value on the injection system control module (N3) should therefore also be read out.

Any fuel gauge faults in the instrument cluster (A1) which are caused by defects in the fuel gauge sensor may also cause faults in the trip computer. By contrast, e.g. if only the journey time function is faulty, the fault is in the trip computer control module (N41) as for this function only the time information is required, which is generated in the trip computer control module (N41) itself.

For this refer to the appropriate function description.

Editorial comment: All the maximum values of the display when the engine is running and vehicle is stationary specified in the Diagnosis Manual correspond to the status when going to press (8.8.97) and may change.