Schematic Reference: Brake Warning System Schematics

1

Did you review the Brake Warning System Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Hydraulic Brakes

1. Turn OFF the ignition for 5 seconds.
2. Ensure the park brake is released.
3. Turn ON the ignition while observing the brake warning indicator.

Does the brake warning indicator illuminate for 3 seconds and then turn OFF?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

1. Install a scan tool.
2. Select the Instrument Panel Cluster Special Functions menu on the scan tool.
3. Command the Brake Lamp Off.

Does the brake warning indicator turn OFF?

Go to Step 4

Go to Step 11

1. Select Input 1 from the Body Control Module Data Display menu on the scan tool.
2. Ensure the park brake is released.
3. Observe the Park Brake status on the scan tool.

Does the scan tool display Released?

Go to Step 5

Go to Step 6

Disconnect the brake fluid level switch harness connector.

Does the brake warning indicator turn OFF?

Go to Step 12

Go to Step 8

Disconnect the park brake switch harness connector.

Does the brake warning indicator turn OFF?

Go to Step 9

Go to Step 7

1. Disconnect from the BCM, the harness connector containing the park brake switch output circuit.
2. Test the park brake switch output 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 14

Go to Step 10

1. Disconnect from the EBCM, the harness connector containing the brake fluid level sensor signal circuit.
2. Test the brake fluid level sensor signal 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 14

Go to Step 13

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

Did you complete the replacement?

Go to Step 14

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Important: Perform the set up procedure for the BCM.

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

Did you complete the replacement?

Go to Step 14

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Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the replacement?

Go to Step 14

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Replace the brake fluid level switch. Refer to Master Cylinder Reservoir Replacement .

Did you complete the replacement?

Go to Step 14

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Important: For vehicles not equiped with UJ1, Go to Step 14

Repair the short to ground in the brake warning indicator control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 15

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Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.

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

Did you complete the replacement?

Go to Step 15

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1. Turn OFF the ignition for 5 seconds.
2. Ensure the park brake is released.
3. Turn ON the ignition while observing the brake warning indicator.

Does the brake warning indicator illuminate for 3 seconds and then turn OFF?

System OK

Go to Step 2