Diagnostic Notes

This procedure is intended to determine whether the cause for loss of or erratic Programmable Speedometer/Odometer Module (PSOM) function is due to the lack of a signal from the RABS Sensor.

There are two basic reasons that PSOM would not receive a signal from the RABS Sensor:

- The RABS sensor or the signal from the RABS sensor is faulty and either not being generated or is not reaching the antilock electronic control module and/or PSOM. In cases where the concern is not intermittent and not reaching the antilock electronic control module, the rear ABS warning light will be on upon vehicle start up and a diagnostic trouble code should be obtained upon RABS II diagnostic trouble code retrieval. Where the concern is intermittent and the rear ABS warning light does NOT come on during vehicle start up, a diagnostic trouble code may still be stored in the antilock electronic control module (see the symptoms chart).

- The wiring or interconnections in the vehicle harness between the antilock electronic control module and the PSOM is faulty. This may lead to erratic PSOM function and is difficult to diagnose.

This procedure will only determine whether the RABS sensor is functioning based upon whether a signal is received at the PSOM. If it is determined that the RABS sensor is sending out a proper signal, diagnose PSOM System.