Circuit Description
The body control module (BCM) supplies battery positive voltage to the reading lamps, underhood lamp, instrument panel (I/P) compartment lamp, and both visor vanity mirror lamps. In the event that any of these lamps were to remain illuminated for more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition.
Voltage for the inadvertent power supply voltage circuit is from the TBC 4 fuse 11 in the underhood fuse block directly through the BCM to this circuit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1480 Battery Rundown Protection Circuit
Conditions for Running the DTC
The battery voltage must be between 9.0-16.0 volts.
Conditions for Setting the DTC
| • | The inadvertent power supply voltage circuit to the reading lamps, underhood lamp, I/P compartment lamp, and both visor vanity mirror lamps is shorted to ground for more than 1 second. |
| • | There is a loss of the instrument panel fuse block TBC 4 battery supply voltage to the BCM for 1 second while one or more of the lamps in the inadvertent power circuit has been activated. |
Action Taken When the DTC Sets
The reading lamps, underhood lamp, I/P compartment lamp, and both visor vanity mirror lamps will not operate.
Conditions for Clearing the MIL/DTC
| • | This DTC will clear on current status after the condition for setting the fault is corrected. |
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
| • | History and current DTCs can be cleared using a scan tool. |
Diagnostic Aids
| • | Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections. |
| • | A short to ground in the inadvertent power supply voltage circuit or the battery positive voltage circuit will cause the TBC 4 fuse to open. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step test determines if the problem exists in the wiring or the BCM.
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After replacement of the BCM you must calibrate the new module for proper operation.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Interior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Inspect the TBC 4 fuse in the underhood fuse block. Is the fuse open? | Go to Step 3 | Go to Step 4 |
Test the inadvertent power supply voltage circuit, and the TBC 4 battery supply voltage to the body control module (BCM) for a short to ground. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 6 | Go to Step 4 | |
4 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- | |
6 |
Does the DTC reset? | Go to Step 2 | System OK |
