GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Brakes 🢒 Park Brake 🢒 Park Brake Will Not Release

Test Description

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

  1. This step tests the park brake switch signal circuit. An open in the park brake switch of the park brake signal circuit will prevent release of the park brake, and illumination of the red brake warning indicator.

    2.

  2. Listen for an audible click from the release solenoid when the park brake relay A operates. Command both the ON and OFF states. Repeat the commands as necessary.

    3.

  3. This step tests for voltage to the park brake release solenoid.

    4.

  4. This step tests supply voltage to the park relay A for an open.

    5.

  5. This step tests to see if relay A is the cause of the failure.

    6.

  6. This step tests for an open in the circuit from the park brake relay A to the park brake release solenoid.

Step

Action

Yes

No

Schematic Reference: Park Brake System Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, with the engine OFF.
  2. Make sure the park brake pedal is in the applied position.
  3. Observe the red brake warning indicator.

Is the red brake warning indicator illuminated?

Go to Step 3

Go to Brake Warning Indicator Inoperative

3

  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, command the park brake relay A ON and OFF.

Did you hear the park brake release solenoid?

Go to Park Brake System Diagnosis

Go to Step 4

4

  1. Unplug the connector to the park brake solenoids.
  2. Install a test light to the terminal A ON connector.
  3. With a scan tool, command the park brake relay A ON and OFF.

Does the test light come ON?

Go to Step 5

Go to Step 6

5

Replace the park brake release solenoid. Refer to Park Brake Release Solenoid Replacement .

Did you complete the replacement?

Go to Step 10

--

6

Test the supply voltage circuit of the park brake relay A for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 7

7

  1. Remove the park brake relay A.
  2. Connect a jumper wire between C3 and C5 in the relay block.

Does the park brake release?

Go to Step 8

Go to Step 9

8

Replace the park brake relay A.

Did you complete the replacement?

Go to Step 10

--

9

Test the supply voltage circuit from the park brake relay A to the park brake release solenoid for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 2

10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2