B1972

DTC B1972 Low Power Driver Fault:

CIRCUIT DESCRIPTION
After the ignition switch is turned to the Lock position, the Body Control Module (BCM) transitions to the High Power Mode (control of the battery guard relay) for 15 minutes and supplies power to the following components:
^ The Radio Receiver.
^ The Radio Interface Module (RIM).
^ The Fuel Tank Filler Door Relay coil.
^ The Rear Compartment Lid Release Relay coil.
^ The Phone (dealer installed).

After the 15 minute time period, the BCM deactivates the High Power Mode and transitions to the Low Power Mode. During the Low Power Mode, the BCM provides memory power to the previous mentioned component. After 3 days of no vehicle activity, the BCM deactivates the output and transitions to the No Controlled Power Mode (the BCM is allowed to go to sleep).

CONDITIONS FOR SETTING THE DTC
The BCM monitors the Low Power output every 300 ms at terminal B1. The fault code is set when the BCM commands the Low Power On and the feedback (short to ground) is low for more than 300 ms.

ACTION TAKEN WHEN THE DTC SETS
^ The BCM deactivates the Low Power output until the ignition has cycled or the BCM receives a wake-up.
^ Stores a DTC 81972 in the BCM memory.

CONDITIONS FOR CLEARING THE DTC
^ The conditions for the fault are no longer present.
^ The use of a scan tool.
^ A history DTC will clear after 50 consecutive ignition cycles if the condition for the fault is no longer present.

DIAGNOSTIC AIDS
The problem may be intermittent if the DTC is a history DTC. Try performing the tests shown while wiggling the wiring and the connectors. Wiggling the wires and the connectors can often cause the malfunction to appear. Refer to Intermittents and Poor Connections. Intermittents and Poor Connections

TEST DESCRIPTION
The following numbers refer to step numbers on the diagnostic table:
2. This test checks for a short to ground. Disconnect all the components from the circuit to get a good reading on the circuit.
3. This test checks for proper voltage and ground input to the BCM. After checking the inputs, the BCM is checked again to see if the DTC resets, indicating an internal circuit failure.