Component Tests and General Diagnostics

COMPASS MINI-TRIP COMPUTER

A diagnostic scan tool is required for checking the Programmable Communications Interface (PCI) Data Bus circuit and the Compass Mini-Trip Computer (CMTC) module. If the CMTC module is not operational, complete the following steps to ensure module has battery power.

1. Remove the overhead console from the headliner, Overhead Console - Removal. Check for battery voltage at the fused B(+) circuit cavity of the CMTC module. If OK, go to STEP 2. If not OK, repair the open fused B(+) circuit as required.
2. Turn the ignition switch to the Off position. Disconnect and isolate the battery negative cable. Check for continuity between the ground circuit cavity of the CMTC module and a good ground. There should be continuity. If OK, go to STEP 3. If not OK, repair the open ground circuit as required.
3. Connect negative battery cable. Turn the ignition switch to the On position. Check for battery voltage at the fused ignition switch output (run/start) circuit cavity of the CMTC module. If OK, the voltage and ground supply to the module is OK at this time. If not OK, repair the open fused ignition switch output (run/start) circuit as required.
NOTE: If the compass functions, but accuracy is suspect, it may be necessary to perform a variance adjustment. This procedure allows the compass unit to accommodate variations in the earth's magnetic field strength, based on geographic location. Adjustments

NOTE: If the compass reading displays a blank, and only "CAL" appears in the display, demagnetizing may be necessary to remove excessive residual magnetic fields from the vehicle. Compass Demagnetizing