Power Mode Mismatch

Power Mode Mismatch

Circuit Description

Normal vehicle serial data communications and module operations will not begin until the system power mode has been identified. Discrete wires from the ignition switch contacts are monitored by a module which acts as the power mode master (PMM) in order to determine the correct power mode. The module which is the PMM communicates the system power mode to all modules on the serial data lines. refer to Body Control System Description and Operation to identify which module is the PMM and the applicable power mode look up table.

Test Description

Step 1 - Step 6:

Step 7 - Step 14:

The numbers below refer to the step numbers on the diagnostic table.
6. This step tests for battery voltage on the incorrect signal circuits.
7. This step tests for no battery voltage on the required signal circuits.
8. If any ignition switch parameters that should be inactive in the present ignition switch position are active, 2 ignition switch signal circuits may be shorted together.
9. This step eliminates open circuits as the cause of the malfunction.