Diagnosis And Testing - Compass Mini-Trip Computer
WARNING: This page is about a different car, the 2004 Dodge Grand Caravan, 2004 Dodge Caravan, and 2004 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
Compass Mini-Trip Computer (CMTC) and Compass Temperature (CT) data is obtained from the Body Control Module (BCM) on the J1850 Data Bus circuit. The CMTC and CT will display dashes (- -) for any of the screens it did not receive the bus messages. The label corresponding to the missing information will be lit. If no compass mini-trip computer data is displayed, check the J1850 Data Bus circuit communications and the BCM. If the brightness level is improper check the J1850 Data Bus circuit.
The DRBIII(R) is recommended for checking the J1850 Data Bus circuit and the BCM. Perform the CMTC, CT self diagnosis before replacing the CMTC or CT module.