1. Turn the ignition switch to the RUN position.
2. Use the scan tool in order to attempt to establish communication with the following components on the class 2 data link:

•	The body control module (BCM)

•	The electronic brake control module (EBCM)

•	The instrument cluster

Are all the modules communicating with the scan tool?

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Go to Step 2

Go to Scan Tool Does Not Communicate with Class 2 Data Line in Wiring Systems.

1. Select instrument panel cluster, special functions, lamp test.
2. Select brake lamp.
3. Command the lamp ON.

Does the brake warning lamp light?

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Go to Step 3

Go to Step 16

1. Select the BCM scan tool data.
2. Monitor the park brake switch status while setting the park brake.

Does park brake switch status cycle from OFF to ON when setting the park brake?

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Go to Step 6

Go to Step 4

1. Disconnect the park brake switch.
2. Using a fused jumper wire, jump pin A to ground.

Does the brake warning lamp light?

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Go to Step 5

Go to Step 8

Replace the park brake switch. Refer to Parking Brake Indicator Switch Replacement in Parking Brakes.

Is the repair complete?

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System OK

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1. Disconnect the brake fluid level switch connector.
2. Using a fused jumper wire, jump pins A to B.

Does the brake warning lamp light?

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Go to Step 7

Go to Step 11

Replace the brake fluid level switch.

Is the repair complete?

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System OK

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Locate the open in CKT 1134 (LT BLU) between the park brake switch and the BCM.

Did you find an open?

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Go to Step 9

Go to Step 10

Repair the open in CKT 1134 (LT BLU) between the park brake switch and the BCM.

Is the repair complete?

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System OK

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

Is the repair complete?

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System OK

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Using a fused jumper wire, jump pin B to ground.

Does the brake warning lamp light?

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Go to Step 12

Go to Step 13

Locate and repair the open in CKT 550 (BLK) between the brake fluid level switch and G104.

Is the repair complete?

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System OK

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Locate the open in CKT 333 (PPL) between the brake fluid level switch and the EBCM.

Did you find an open?

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Go to Step 14

Go to Step 15

Repair the open in CKT 333 (PPL) between the brake fluid level switch and the EBCM.

Is the repair complete?

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System OK

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Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System.

Is the repair complete?

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System OK

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Replace the instrument cluster. Refer to Instrument Cluster Replacement .

Is the repair complete?

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Go to Instrument Cluster System Check .

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