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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Brake Warning Indicator Always On

Brake Warning Indicator Always On Without DRLs

Circuit Description

The brake warning indicator illuminates when ground is applied to the brake warning indicator control circuit.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Ground is applied to the ABS pressure differential sensor signal circuit if the scan tool displays On.

    2.

  2. This step tests for a shorted brake pressure differential switch.

    3.

  3. This step tests if the EBCM is applying ground to the brake warning indicator.

    4.

  4. This step tests for a shorted park brake warning lamp switch.

Step

Action

Yes

No

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

2
  1. Turn OFF the ignition.
  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

3
  1. Install a scan tool.
  2. Select the 4WAL 3 Sensor Current Diagnostic Trouble Codes function on the scan tool.

Does the scan tool display DTC C0286 AND any other ABS disabling DTC?

Go to Diagnostic Trouble Code (DTC) List in Antilock Brake System

Go to Step 4

4

  1. Select the 4WAL 3 Sensor Data Display function on the scan tool.
  2. Observe the Brake Warning Lamp Command.

Does the scan tool display On?

Go to Step 5

Go to Step 8

5

Disconnect the brake pressure differential switch harness connector. Refer to Combination Valve Replacement .

Does the brake warning indicator turn OFF?

Go to Step 14

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Reconnect the brake pressure differential switch harness connector.
  3. Disconnect the 10-way EBCM harness connector. Refer to Electronic Brake Control Module Replacement in Antilock Brake System.
  4. Turn ON the ignition.

Does the brake warning indicator turn OFF?

Go to Step 11

Go to Step 7

7

Repair the short to ground in the ABS pressure differential sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 15

--

8

Disconnect the park brake warning lamp switch harness connector. Refer to Parking Brake Indicator Switch Replacement in Park Brake.

Does the brake warning indicator turn OFF?

Go to Step 13

Go to Step 9

9
  1. Turn OFF the ignition.
  2. Disconnect the instrument panel cluster harness connector. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
  3. Connect a test lamp between the battery positive voltage circuit and the brake warning indicator control circuit.
  4. Turn ON the ignition.

Does the test lamp remain illuminated?

Go to Step 10

Go to Step 12

10

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

--

11

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

Important: Use the scan tool in order to perform the Tire Size Calibration procedure.

Did you complete the replacement?

Go to Step 15

--

12

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

Did you complete the replacement?

Go to Step 15

--

13

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

Did you complete the replacement?

Go to Step 15

--

14

Replace the brake pressure differential switch. Refer to Combination Valve Replacement .

Did you complete the replacement?

Go to Step 15

--

15
  1. Turn OFF the ignition for 5 seconds.
  2. 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 3

Brake Warning Indicator Always On W/DRLs

Circuit Description

The brake warning indicator illuminates when ground is applied to the brake warning indicator control circuit.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Ground is applied to the ABS pressure differential sensor signal circuit if the scan tool displays On.

    2.

  2. This step tests for a shorted brake pressure differential switch.

    3.

  3. This step tests if the EBCM is applying ground to the brake warning indicator.

    4.

  4. This step tests for a shorted park brake warning lamp switch.

    5.

  5. The harness connector of the DRL control module contains 2 separate park brake switch signal circuits.

    6.

  6. This step tests the brake warning indicator control circuit for a short to ground by substituting the IPC and the brake warning indicator lamp with a test lamp.

Step

Action

Yes

No

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

2
  1. Turn OFF the ignition.
  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

3
  1. Install a scan tool.
  2. Select the 4WAL 3 Sensor Current Diagnostic Trouble Codes function on the scan tool.

Does the scan tool display DTC C0286 AND any other ABS disabling DTC?

Go to Diagnostic Trouble Code (DTC) List in Antilock Brake System

Go to Step 4

4

  1. Select the 4WAL 3 Sensor Data Display function on the scan tool.
  2. Observe the Brake Warning Lamp Command.

Does the scan tool display On?

Go to Step 5

Go to Step 8

5

Disconnect the brake pressure differential switch harness connector. Refer to Combination Valve Replacement .

Does the brake warning indicator turn OFF?

Go to Step 20

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Reconnect the brake pressure differential switch harness connector.
  3. Disconnect the 10-way EBCM harness connector. Refer to Electronic Brake Control Module Replacement in Antilock Brake System.
  4. Turn ON the ignition.

Does the brake warning indicator turn OFF?

Go to Step 16

Go to Step 7

7

Repair the short to ground in the ABS pressure differential sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 21

--

8

Disconnect the park brake warning lamp switch harness connector. Refer to Parking Brake Indicator Switch Replacement in Park Brake.

Does the brake warning indicator turn OFF?

Go to Step 18

Go to Step 9

9
  1. Turn OFF the ignition.
  2. Remove the DRL control module circuit board. Refer to Daytime Running Lights (DRL) Control Module Replacement in Lighting Systems.
  3. Turn ON the ignition.

Does the brake warning indicator turn OFF?

Go to Step 10

Go to Step 14

10

  1. Turn OFF the ignition.
  2. Disconnect the ignition switch harness connector. Refer to Ignition and Start Switch Replacement in Steering Wheel and Column.
  3. Test the park brake switch signal circuit (ignition switch side) for a short to ground. Refer to Circuit Testing in Wiring Systems.

Is the park brake switch signal circuit shorted to ground within the ignition switch?

Go to Step 19

Go to Step 11

11

  1. Reconnect the ignition switch harness connector.
  2. Test both of the park brake switch signal circuits 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 21

Go to Step 12

12

Test the brake warning indicator control circuit for a short to ground between the DRL control module circuit board and the underhood fuse block. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 13

13

Replace the DRL control module circuit board. Refer to Daytime Running Lights (DRL) Control Module Replacement in Lighting Systems.

Did you complete the replacement?

Go to Step 21

--

14

  1. Turn OFF the ignition.
  2. Remove the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
  3. Connect a test lamp between the battery positive voltage circuit and the brake warning indicator control circuit at the instrument panel cluster harness connector.
  4. Turn ON the ignition.

Does the test lamp remain illuminated?

Go to Step 15

Go to Step 17

15

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 21

--

16

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

Important: Use the scan tool in order to perform the Tire Size Calibration procedure.

Did you complete the replacement?

Go to Step 21

--

17

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

Did you complete the replacement?

Go to Step 21

--

18

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

Did you complete the replacement?

Go to Step 21

--

19

Replace the ignition switch. Refer to Ignition and Start Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 21

--

20

Replace the brake pressure differential switch. Refer to Combination Valve Replacement .

Did you complete the replacement?

Go to Step 21

--

21

  1. Turn OFF the ignition for 5 seconds.
  2. 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 3