Circuit Description
When the headlamp switch is turned to the PARK or HEAD position, the body control module (BCM) applies battery positive voltage to the instrument panel (I/P) courtesy lamps. When a door is opened, the door latch assembly applies a ground to the BCM. The BCM supplies battery positive voltage to the courtesy lamp supply voltage circuit and applies a ground to the courtesy lamps control circuit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1482 Supply Voltage Circuit Low
Conditions for Running the DTC
Voltage supplied to the BCM is in the normal operating range, approximately 9-14 volts.
Conditions for Setting the DTC
| • | The BCM detects a low when a high is expected in either the instrument panel lamps supply voltage circuit or the courtesy lamp supply voltage circuit. |
| • | The condition above must be present for more then 0.1 second. |
Action Taken When the DTC Sets
| • | The IS Lamps Fuse opens. |
| • | The courtesy lamps are inoperative. |
| • | The I/P courtesy lamps are inoperative. |
| • | The BCM stores DTC B1482 in memory. |
| • | The BCM stores DTC B2627 in memory. |
Conditions for Clearing the MIL/DTC
| • | A current DTC B1482 and B2627 clears when the BCM no longer detects a short to ground in the instrument panel lamps supply voltage circuit or the courtesy lamps supply voltage circuit. |
| • | A history DTC B1482 and B2627 clears after 100 consecutive ignition cycles. |
Diagnostic Aids
| • | The IS Lamps Fuse opens when there is a short to ground in either the instrument panel lamps supply voltage circuit or the courtesy lamps supply voltage circuit and must be replaced before doing any diagnostics. |
| • | If the DTC B1482 or B2627 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections. |
| • | The following conditions may cause an intermittent malfunction to occur: |
| - | An intermittent short to ground in the instrument panel lamps supply voltage circuit or the courtesy lamps supply voltage circuit. |
| - | The BCM is intermittently shorted to ground. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Interior Lights Dimming Schematics and Interior Lights Schematics Connector End View Reference: Master Electrical Component List | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the IS Lamps Fuse open? | Go to Step 4 | Go to Step 3 |
3 |
Are lamps illuminated? | Go to Diagnostic Aids | Go to Step 5 |
4 |
Important: A short to ground on either the courtesy lamp supply voltage circuit or the instrument panel lamps supply voltage circuit will cause the IS Lamps Fuse to open. You must replace this fuse as needed to ensure proper diagnosis. Test the courtesy lamp supply voltage circuit a short to ground. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
5 |
Important: A short to ground on either the courtesy lamp supply voltage circuit or the instrument panel lamps supply voltage circuit will cause the IS Lamps Fuse to open. You must replace this fuse as needed to ensure proper diagnosis. Test the instrument panel lamps supply voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
6 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 7 | -- |
7 |
Does the DTC reset? | Go to Step 2 | System OK |
