Chart F - DERM Cannot Communicate Through Serial Data Line: Description
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1995 GMC Vandura Special, 1995 GMC Vandura, 1995 GMC Rally Camper Special, 1995 GMC Rally, and 1995 Chevrolet Sportvan. However, it is still accessible from the selected car via links, so may be relevant.
When DERM recognizes that IGNITION 1 voltage applied to terminal A9 and A10 is in normal operating voltage range, AIR BAG warning light is flashed 7 times to verify operation. At this time DERM performs TURN-ON tests followed by CONTINUOUS MONITORING tests. When no malfunctions are detected, DERM proceeds to INITIATOR ASSEMBLY RESISTANCE TEST. When a malfunction is detected, DERM sets a current DTC and illuminates AIR BAG warning light. DERM will clear current DTCs and move them to a history file when malfunction is no longer detected and/or ignition switch is cycled, except for DTC 51. DTC 51 can only be cleared using a scan tool CLEAR CODES command.
NOTE:
Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS.
- Confirms proper operation of scan tool.
- Incorrect connection to data link connector will prevent communications from being established.
- Checks for general SERIAL DATA line malfunction.
- Checks for a short to ground in SERIAL DATA line.
- Checks for a short to voltage in SERIAL DATA line.
- Checks for an open in SERIAL DATA line.
- Checks whether malfunction is due to an open in SERIAL DATA line or DERM.
WARNING:
To avoid air bag deployment and injury when trouble shooting system, only use test equipment specified in diagnostic charts. Under no circumstances should battery powered test equipment or test light be used. Carefully follow all instructions.