The Door Control Modules (DCMs) use information from other systems in order to execute some functions. Therefore, before further diagnosis, review the general information on how the DCMs operates and how each system interacts with the DCMs. This will save diagnostic time, future misdiagnosis, and unnecessary parts replacement.
Use a scan tool in order to diagnose the DCMs when referred to in diagnostic procedures. In addition to displaying DTCs, the DCMs displays the input status and the data values used. The DCMs can also command many of its subsystems ON and OFF. Any of these features can be selected using the scan tool.
Become very familiar with the DCMs capabilities and diagnostic features. These self-diagnostic features are referenced in the DTC tables and are very useful in diagnosing non-DTC setting malfunctions as well.
Replace a DCM only if the diagnostic procedures specifically direct you to do so. Every input to the DCMs and every output from the DCMs is short to ground/short to battery protected. Therefore, a DCM does not automatically need to be replaced when a short is found in the wiring. Repair the wiring first. Then check the system for further problems. Most system malfunctions are traceable to faulty wiring and connectors, and occasionally components. The DCMs are very reliable and not the likely cause of a system malfunction. A DCM replacement before a complete diagnosis will usually result in a recurrence of the original complaint malfunction.
History DTCs
The DCMs have the ability to store DTCs as history codes only. Therefore, when a DTC is stored , the DCMs will display all DTCs as history even thought the malfunction is current. Always diagnose history DTCs the same way as current DTCs by performing the applicable DTC table. If a DTC table was preformed and the malfunction is intermittent (no longer present), refer to Intermittents and Poor Connections .
