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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Savana 🢒 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. This step tests for a shorted brake pressure differential switch.

    2.

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

    3.

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

    4.

  4. 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.

    5.

  5. This step tests for a shorted ignition switch.

    6.

  6. If no short is found, the brake warning indicator supply voltage 2 circuit is shorted to ground or the p/b booster fluid flow and pressure alarm delay module is applying ground to the circuit. Another malfunction is preventing the p/b booster fluid flow alarm from sounding.

Step

Action

Yes

No

Schematic Reference: Brake Warning System Schematics

Important: The brake warning indicator remains illuminated when the ignition is ON, with the engine OFF if the vehicle is equipped with a power brake booster fluid flow alarm (UJ1). Therefore, if the vehicle being serviced is so equipped, the engine must be started each time this diagnostic table instructs you to turn ON the ignition.

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 status.

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 18

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.
  4. Turn ON the ignition.

Does the brake warning indicator turn OFF?

Go to Step 13

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 19

--

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 15

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, Gauges, 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 14

10

  1. Turn OFF the ignition.
  2. Reconnect the IPC harness connector.
  3. Disconnect the ignition switch harness connector. Refer to Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Standard or Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt.
  4. Test the park brake switch signal circuit (ignition switch) 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 16

Go to Step 11

11

Important: For vehicles not equipped with UJ1, Go to Step 12 .

  1. Turn OFF the ignition.
  2. Reconnect the ignition switch harness connector.
  3. Disconnect connector C208.
  4. Turn ON the ignition.

Does the brake warning indicator turn OFF?

Go to Step 17

Go to Step 12

12

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 19

--

13

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 19

--

14

Replace the Instrument Panel Cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges, and Console.

Did you complete the replacement?

Go to Step 19

--

15

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 19

--

16

Replace the ignition switch. Refer to Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Standard or Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt.

Did you complete the replacement?

Go to Step 19

--

17

Test the brake warning indicator control circuit for a short to ground between connector C208 and the inline diode D202. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Brake Warning Alarm Always On

18

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

Did you complete the replacement?

Go to Step 19

--

19
  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 2

Brake Warning Indicator Always On DRL equipped

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

    2.

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

    3.

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

    4.

  4. This step tests if the DRL control module is applying ground to the brake warning indicator.

    5.

  5. This step tests for a shorted ignition switch.

    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.

    7.

  7. If no short is found, the brake warning indicator supply voltage 2 circuit is shorted to ground or the p/b booster fluid flow and pressure alarm delay module is applying ground to the circuit. Another malfunction is preventing the p/b booster fluid flow alarm from sounding.

Step

Action

Yes

No

Schematic Reference: Brake Warning System Schematics

Important: The brake warning indicator remains illuminated when the ignition is ON, with the engine OFF if the vehicle is equipped with a power brake booster fluid flow alarm (UJ1). Therefore, if the vehicle being serviced is so equipped, the engine must be started each time this diagnostic table instructs you to turn ON the ignition.

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 status.

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 22

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 17

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 23

--

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 19

Go to Step 9

9

  1. Turn OFF the ignition.
  2. Disconnect the daytime running lamps control module harness connector. 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 13

10

  1. Turn OFF the ignition.
  2. Test the park brake switch signal circuit for a short to ground. Refer to Circuit Testing in Wiring Systems.

Is the park brake switch signal circuit shorted to ground?

Go to Step 11

Go to Step 14

11

  1. Disconnect the ignition switch harness connector. Refer to Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Standard or Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt.
  2. Test the park brake switch signal circuit (NOT the 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?

Go to Step 12

Go to Step 20

12

Repair the short to ground in the park brake switch signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

13

Important: For vehicles not equipped with UJ1, Go to Step 15 .

  1. Turn OFF the ignition.
  2. Reconnect the daytime running lamps control module harness connector.
  3. Disconnect connector C208.
  4. Turn ON the ignition.

Does the brake warning indicator turn OFF?

Go to Step 21

Go to Step 15

14

Replace the daytime running lamps control module. Refer to Daytime Running Lights (DRL) Control Module Replacement in Lighting Systems.

Did you complete the replacement?

Go to Step 23

--

15

  1. Turn OFF the ignition.
  2. Reconnect connector C208 if step 13 was performed.
  3. Remove the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges, and Console.
  4. Connect a test lamp between the battery positive voltage circuit and the brake warning indicator control circuit at the instrument panel cluster harness connector.
  5. Turn ON the ignition.

Does the test lamp remain illuminated?

Go to Step 16

Go to Step 18

16

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 23

--

17

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 23

--

18

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

Did you complete the replacement?

Go to Step 23

--

19

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 23

--

20

Replace the ignition switch. Refer to Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Standard or Ignition Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt.

Did you complete the replacement?

Go to Step 23

--

21

Test the brake warning indicator control circuit for a short to ground between connector C208 and the inline diode D202. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 23

Go to Brake Warning Alarm Always On

22

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

Did you complete the replacement?

Go to Step 23

--

23
  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