B1379

CIRCUIT DESCRIPTION
Ignition 3 input to the body control module (BCM) from the ignition switch, is used to determine the power mode the vehicle. When the BCM senses that the ignition 3 input is open, DTC B1379 sets.

CONDITIONS FOR SETTING THE DTC
The ignition 3 input is inactive after the ignition 1 input has been active for 20 seconds.

CONDITION FOR RUNNING THE DTC
^ The ignition switch is on.
^ At least 20 seconds has elapsed since the ignition switch was cycled on.

ACTION TAKEN WHEN THE DTC SETS
^ The SERVICE VEHICLE SOON indicator illuminates.
^ The check gauges chime sounds.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC B1379 will clear when the malfunction is no longer present and the ignition switch is cycled.
^ BCM history codes will clear after 100 ignition cycles (from OFF to ON) with no current codes active during the 100 ignition cycles.

DIAGNOSTIC AIDS
If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while agitating the related wiring and connectors. This action often causes the malfunction to manifest.

TEST DESCRIPTION

Steps 1-6:

Steps 7-15:

The numbers listed below refer to the numbers on the diagnostic table.
4. This step determines if ignition 3 is shorted to ground.
5. This step determines if the BCM is internally shorted.
6. This step determines if the cruise control module is internally shorted.
7. This step determines if voltage is supplied from the battery to the fuse.