When the headlamp switch is turned to the PARK or HEAD position, the body control module (BCM) applies battery positive voltage to the 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.
Voltage supplied to the BCM is in the normal operating range, approximately 9-14 volts.
| • | 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 seconds | 
| • | The BCM L Fuse opens. | 
| • | The courtesy lamps are inoperative. | 
| • | The I/P courtesy lamps are inoperative. | 
| • | The BCM stores DTC B1482 in memory. | 
| • | The BCM store DTC B2627 in memory. | 
| • | 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. | 
| • | The BCM L 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 in Wiring Systems. | 
| • | 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 Lighting Diagnostic System Check?  | Go to Step 2  | |
2  | 
 Does the BCM L 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 BCM L 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 in Wiring Systems. 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 BCM L 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 in Wiring Systems. Did you find and correct the condition?  | Go to Step 7  | Go to Step 6  | 
6  | 
 Important: Perform the set up procedure for the Body Control Module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control Systems. Replace the BCM. Refer to Body Control Module Replacement in Body Control System. Did you complete the replacement?  | Go to Step 7  | --  | 
7  | 
 Does the DTC reset?  | Go to Step 2  | System OK  |