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

1. Test the body control module (BCM) for DTCs. Refer to Diagnostic Trouble Code (DTC) List/Type in Body Control System.
2. Correct any of the current DTCs before proceeding with this diagnosis.

Are all of the code setting conditions corrected?

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Go to Step  2

Go to Step  3

1. Connect a scan tool to the data link connector (DLC).
2. Turn the headlamp switch to the PARK position.
3. Use the scan tool in order to command the fog lamps on.

Do the fog lamps light?

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Go to Step  4

Go to Step  5

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Is the repair complete?

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Go to Exterior Lights System Check

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Backprobe the BCM connector C3 using a fused jumper between terminal A4 and ground.

Is the fog lamp ON input received by the scan tool?

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Go to Step  6

Go to Step  7

1. Exchange the fog lamp relay with a known good relay from the right IP junction block.
2. Use the scan tool in order to command the fog lamps on.

Do the fog lamps light?

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Go to Step  8

Go to Step  9

1. Disconnect the fog lamp switch connector.
2. Connect a fused jumper between terminal D (terminal A for Oldsmobile) of the fog lamp switch connector and ground.

Is the fog lamp ON input received by the scan tool?

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Go to Step  11

Go to Step  12

Replace the BCM. Refer to the following procedures:

Is the repair complete?

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Go to Exterior Lights System Check

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Replace the faulty relay.

Is the repair complete?

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Go to Exterior Lights System Check

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1. Disconnect the right junction block connector C1.
2. Disconnect the BCM connector C1.
3. Use a DMM in order to measure the resistance between terminal F3 of the junction block connector and terminal A2 of the BCM.

Is the resistance within the specified range?

0-2 ohms

Go to Step  10

Go to Step  15

Replace the right IP junction block. Refer to Relay/Fuse Center Replacement in Wiring Systems.

Is the repair complete?

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Go to Exterior Lights System Check

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Connect a fused jumper between terminal A and terminal D (terminal A and terminal B for Oldsmobile) of the fog lamp switch connector.

Is the fog lamp ON input received by the scan tool?

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Go to Step  13

Go to Step  14

Repair the open in CKT 192 between the BCM and the fog lamp switch. 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 fog lamp switch.

Is the repair complete?

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Go to Exterior Lights System Check

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Repair the open in CKT 251 between the fog lamp switch and the ground splice pack G204. 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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Repair the open in CKT 1317 between BCM connector C1 terminal A2 and the right junction block connector C1 terminal F3. 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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