B1372

DTC B1372

CIRCUIT DESCRIPTION




Normal vehicle class 2 communication will not commence until the system power mode has been identified. The body control module (BCM) communicates the system power mode to all the modules connected to the class 2 serial data circuit. The BCM monitors the state of the ignition 1 voltage circuit, accessory voltage circuit and the engine run flag (ERF) in order to determine the present system power mode. The ERF is a serial data message from the engine controller.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTC:
DTC B1372 Device Ignition 1 (Run/Crank) Circuit Low

CONDITIONS FOR RUNNING THE DTC
The only requirements are voltage and ground.

CONDITIONS FOR SETTING THE DTC
The BCM has detected the ignition 1 voltage circuit is open or shorted to ground for greater than 1.2 seconds when the accessory voltage circuit is high and the engine run flag is true.

ACTION TAKEN WHEN THE DTC SETS
- There is no cluster illumination during bulb check.
- The malfunction indicator lamp (MIL) is illuminated.
- BCM (IGN 1) fuse will open with a short to ground present.

CONDITIONS FOR CLEARING THE MIL/DTC
- A current DTC clears and the MIL is turned OFF when the fault is no longer present.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the fault.

DIAGNOSTIC AIDS




refer to Diagnostic Aids for Circuit Testing and Wiring Repair procedures.

TEST DESCRIPTION

Steps 1 - 7:

The numbers below refer to the step numbers on the diagnostic table.
3. This step tests the inactive signal circuit for an open or a high resistance.