Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

1. Disconnect the rear lamp assembly connector
2. Connect a test lamp between one of the following terminals of the inoperative rear lamp assembly connector and ground:

•	Terminal E (Pontiac LH)

•	Terminal B (Pontiac RH)

•	Terminal D (Olds)

3. Depress the brake pedal.

Does the test lamp light?

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Go to Step 2

Go to Step 3

1. Connect a test lamp between terminal C (ground) and one of the following terminals of the inoperative rear lamp assembly connector:

•	Terminal E (Pontiac LH)

•	Terminal B (Pontiac RH)

•	Terminal D (Olds)

2. Depress the brake pedal.

Does the test lamp light?

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Go to Step 4

Go to Step 5

Repair the open in CKT 20 between the left IP junction block and the inoperative rear lamp assembly. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Exterior Lights System Check

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Replace the inoperative rear lamp assembly.

Is the repair complete?

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Go to Exterior Lights System Check

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Repair the open in CKT 750 or CKT 850 between the inoperative rear lamp assembly and the ground splice pack. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Exterior Lights System Check

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