Chart G DERM Cannot Communicate Through the Serial Data Circuit

Wiring Diagram:

***This procedure has been updated by TSB 439003, March 1994***

CIRCUIT DESCRIPTION
When the DERM recognizes "Ignition 1" voltage, applied to terminal "A9" and "A10", is in the normal operating voltage range, the "AIR BAG" warning lamp is flashed 7 times to verify operation. At this time the DERM performs "Turn-ON" tests followed by "Continuous Monitoring" tests. When no malfunctions are detected the DERM proceeds to the "Initiator Assembly Resistance Test." When a malfunction is detected the DERM sets a current diagnostic trouble code and illuminates the "AIR BAG" warning lamp. The DERM will clear current diagnostic trouble codes and move them to a history file when the malfunction is no longer detected and/or the ignition switch is cycled, except for DTC 51. DTC 51 can only be cleared using a scan tool "Clear Codes" command.

TEST DESCRIPTION

Number(s) below refer to circled number(s) on the diagnostic chart.

1. An improper connection to the data link connector will prevent communications from being established.

2. This test checks for a short to ground in the "Serial Data" circuit.

3. This test checks for an open in the "Serial Data" circuit.

4. This test checks for a short to B + in the "Serial Data" circuit. Once the integrity of the "Serial Data" circuit has been confirmed, including proper connections, the DERM must be malfunctioning.