B1973

DTC B1973 High Power Control Fault:

CIRCUIT DESCRIPTION
The Body Control Module (BCM) controls the battery guard relay by grounding the relay coil at terminal D1. Once the relay is energized it supplies battery power to the following components:
^ The Radio Receiver
^ The Radio Interface Module
^ The Fuel Tank Filler Door Relay Coil
^ The Rear Compartment Lid Release Relay Coil
^ The Cellular Telephone (dealer installed) When the ignition switch is turned to the Lock position the BCM transitions to the High Power Mode. In this mode, the BCM is still in control of the battery guard relay and will continue to supply battery power for 15 minutes to the previously mentioned components.

CONDITIONS FOR SETTING THE DTC
The BCM monitors the output to the battery guard relay every second at terminal D1. The fault code is set when the feedback goes high (short to B+) for 2 or more seconds.

ACTION TAKEN WHEN THE DTC SETS
^ Low Power Mode is deactivated if the fault occurs during this phase.
^ Stores a DTC B1973 in the BCM memory.

CONDITIONS FOR CLEARING THE DTC
^ The BCM does not detect the malfunction for one monitoring cycle.
^ A history DTC will clear after 50 consecutive ignition cycles if the fault is no longer present.
^ The use of a Scan Tool.

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 wiring 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 the step numbers on the diagnostic table:
2. This test checks for a circuit problem (short to B+) external to the BCM.
3. This test checks for proper voltage to the BCM and check for proper ground input to the BCM. After checking these inputs, the BCM is checked again to see if the DTC resets, indicating an internal failure.