B1508

CIRCUIT DESCRIPTION

Schematic:

The Body Control Module (BCM) controls the load management feature. The load management feature can turn off the rear defogger and the heated seats when the vehicle is in a condition where the vehicle electrical load may discharge the battery. When the BCM detects that the system voltage is low, the BCM will remove power from the load management control circuit. Since the load management control circuit supplies power to the rear defogger relay and the heated seats, these devices will no longer operate until the BCM restores power to the load management control circuit.

CONDITIONS FOR RUNNING THE DTC
The BCM must be commanding the load management circuits off.

CONDITIONS FOR SETTING THE DTC
^ The BCM detects a short to B+ or open in the load management control circuit when the BCM is trying to de-energize the rear defogger relay control circuits and shut off the heated seats.
^ The condition above must be present for more than 0.3 seconds.

ACTION TAKEN WHEN THE DTC SETS
The BCM stores DTC B1508 in memory.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC B1508 will clear if the short to B+ or open in the load management control circuit is no longer detected by the BCM.
^ A history DTC B1508 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
^ A scan tool may be used to clear the DTC.

DIAGNOSTIC AIDS
^ If the DTC B1508 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ The following conditions may cause an intermittent malfunction to occur:
- An intermittent short to battery or open in the load management control circuit.
- The rear defogger relay coil is intermittently shorted to B+ or open internally.

TEST DESCRIPTION

Step 1 - 6:

The number(s) below refer to the step number(s) on the diagnostic table.
2. Verifies that the BCM is providing voltage to the rear defogger relay and the heated seat switch (if equipped).
3. Tests for a short to battery or open in the load management control circuit.