GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC K Pickup - 4WD 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C0288 or C088 Brake Warning Lamp Circuit Shorted to B+

Circuit Description

The red BRAKE warning lamp is supplied ignition voltage through the GAUGES fuse. The BRAKE warning lamp can be illuminated by the EBCM, Daytime Running Lights Module (DRL) or Brake Pressure Warning Switch. If a DTC C0288 sets, the EBCM will store in memory but will not disable the ABS. If a DTC C0288 is in memory, the EBCM will not attempt to perform a BRAKE warning lamp bulb check at startup. Also the EBCM will not attempt to use the BRAKE indicator lamp as a backup if the ABS indicator lamp operation is inhibited by a DTC C0286.

Conditions for Running the DTC
    • The ignition switch is in the RUN position.
    • The bulb check is complete.

Conditions for Setting the DTC
    • High voltage present on the BRAKE warning lamp circuit when the circuit is expected to be low (lamp commanded on by the EBCM)
    • Anything that keeps the Brake warning lamp circuit high when the lamp is supposed to be illuminated (such as a short to voltage on CKT  33)

Action Taken When the DTC Sets

No action taken, the ABS is not disabled.

Conditions for Clearing the MIL/DTC
    • Repair the conditions responsible for setting the DTC.
    • Use the Scan Tool Clear DTCs function.

Diagnostic Aids

DTC C0288 is usually set by a short to voltage in the wiring between the brake warning lamp and the EBCM.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Use the scan tool in order to verify BRAKE indicator lamp operation.

    2.

  2. This step determines if a short to voltage condition is responsible for setting the DTC.

    3.

  3. This step determines if an open circuit condition is responsible for setting the DTC.

Step

Action

Value(s)

Yes

No

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the BRAKE indicator lamp ON and OFF.

Does the BRAKE indicator lamp turn ON and OFF with each command?

--

Go to Diagnostic Aids

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the 10-way EBCM harness connector.
  3. Remove the GAUGES fuse.
  4. Turn ON the ignition, with the engine OFF.
  5. Using a J 39200 digital multimeter (DMM), measure the voltage between the BRAKE indicator lamp control circuit of the 10-way EBCM harness connector and ground.

Does the voltage measure greater than the specified range?

10 volts

Go to Step 5

Go to Step 4

4

  1. Install the GAUGES fuse.
  2. Disconnect the instrument cluster harness connector.
  3. Using a J 39200 DMM, test for an open in the BRAKE indicator lamp control circuit between the 10-way EBCM harness connector and the instrument cluster harness connector.

Does the J 39200 DMM measure less than the specified range?

1.0 ohms

Go to Step 7

Go to Step 6

5

Test the BRAKE indicator lamp control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 6

6

Test the BRAKE indicator lamp control circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 7

7

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Important: Perform the set up procedure for the EBCM .

Did you complete the replacement?

--

Go to Step 8

--

8
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK