Identifying Vehicle Communication Problems
Battery must be fully charged before proceeding. Connect scan tool to Data Link Connector (DLC) to retrieve messages. Ensure ground circuit has continuity at terminal No. 4 on DLC. Ensure 12 volts exists at terminal No. 16 on DLC. See following list of vehicle communication symptoms and scan tool fault messages. Proceed to appropriate test. Always turn ignition off prior to disconnecting any module connector.
- BATTERY IOD DISCONNECT AT BCM
- BCM EEPROM CHECKSUM FAILURE
- BCM FLASH CHECKSUM FAILURE
- BCM J1850 BUS MESSAGE FAULTS - MESSAGES NOT RECEIVED
- BUS +/- SIGNAL OPEN FROM BCM
- BCM MATURED FAULT PRESENT
- DDM MESSAGE NOT RECEIVED
- BUS +/- SIGNALS OPEN FROM DDM
- MIC MESSAGE NOT RECEIVED BY BCM
- PCM MESSAGE NOT RECEIVED BY BCM
- PDM MESSAGE NOT RECEIVED BY BCM
- BUS +/- SIGNALS OPEN FROM PDM
- BUS +/- SIGNALS OPEN FROM ELECTRONIC VEHICLE INFORMATION CENTER
- BUS +/- SIGNALS OPEN FROM INSTRUMENT CLUSTER
- BUS +/- SIGNALS OPEN FROM SENTRY KEY IMMOBILIZER MODULE (SKIM)
- COMPLETE PCI BUS FAILURE
- NO RESPONSE FROM ACM
- NO RESPONSE FROM CAB CONTROLLER
- NO RESPONSE FROM PCM (PCI BUS)
- NO RESPONSE FROM PCM (SCI BUS)
- NO RESPONSE FROM TCM
- PCI BUS SHORT TO BATTERY
- PCI BUS SHORT TO GROUND