Diagnostic Aids

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

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.

DTC B2627

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	Go to Diagnostic System Check - Lighting Systems
2	Turn the ignition to the OFF position. Turn the headlamp switch to the OFF position. Open the passenger door. Replace the BCM L fuse. Does the BCM L fuse open?	Go to Step 4	Go to Step 3
3	Turn the ignition to the RUN position. Turn the headlamp switch to the park position. Observe the I/P courtesy lamps. 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	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	Go to Step 2	System OK