The lock switch or lock switch circuit that failed and generated this DTC is wired to either the driver door switch assembly (DDSA), or the front passenger door module (PDM). The DDSA and the PDM supply voltage to the contacts of both the lock and unlock signal circuits of their respective lock switch. The DDSA and the PDM also supply a ground to their associated lock switch. When the normally open contacts of one of the switches are closed to ground, the associated door module interprets this switch signal and converts it to a digital message, which is then sent, via the power door serial data circuit, to the driver door module (DDM). The DDM sends the switch message to the rear integration module (RIM), which is the master of all lock operations, as a class 2 message. The RIM checks all other vehicle information sent out over the class 2 serial data line to determine if vehicle conditions are correct for a lock or unlock request to be performed. If conditions are correct, the RIM sends its OK to the DDM via class 2. When the OK message is received, the DDM sends the required signal to all other door modules via the power door serial data line.

This diagnostic procedure supports the following DTCs:

The DDM and PDM must be powered in communications with each other and can not have B1327 - Battery Voltage Low or B1328 - Battery Voltage High set for these DTCs to set.

If the DDM receives the message that either a passenger door lock switch circuit is closed to ground for more than 30 continuous seconds or a DDSA lock switch circuit is closed to ground for more than 255 seconds (4.25 minutes), the DDM sets a lock switch circuit DTC.

The DDM ignores any message from the lock switch designated by the DTC and prevents lock movement from the switch. The DDM will respond to other lock switch messages.

The DDM clears this current DTC when the switch message is no longer received and stores a history DTC. The history DTC will clear either after 50 OFF/ON ignition switch cycles without a repeated failure or in response to a scan tool command.

The numbers below refer to the step numbers on the diagnostic table.

2. This step checks the module input state using the normal input status.

3. This step checks to see that the input is seen by the module.

4. This step checks to see that the signal lines to the module are open with the switch removed.

5. This step determines if the signal circuits are shorted.