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

Test Description

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

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

    2.

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

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 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.

Does the park brake relay A turn ON and OFF with each command?

Go to Step 3

Go to Step 4

3

With a scan tool, command the park brake relay B ON and OFF.

Does the park brake relay B turn ON and OFF with each command?

Go to Step 6

Go to Step 5

4
  1. Turn OFF the ignition.
  2. Disconnect the body control module (BCM).
  3. Turn ON the ignition, with the engine OFF.
  4. Attempt to set the park brake.

Does the park brake set?

Go to Step 11

Go to Step 8

5
  1. Turn OFF the ignition.
  2. Disconnect the BCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Attempt to set the park brake.

Does the park brake set?

Go to Step 11

Go to Step 9

6

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

Did you find and correct the condition?

Go to Step 19

Go to Step 7

7

Test the supply voltage circuit of the park brake relay B for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 10

8

Test the control circuit of the park brake relay A for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 15

9

Test the control circuit of the park brake relay B for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 16

10

Inspect for poor connections at the harness connector of the park brake release solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 12

11

Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 18

12

Inspect the park brake system for proper operation. Refer to Park Brake System Diagnosis .

Did you find and correct the condition?

Go to Step 19

Go to Step 13

13

Inspect the disc brake system for proper operation. Refer to Disc Brake System Diagnosis .

Did you find and correct the condition?

Go to Step 19

Go to Step 14

14

Inspect the hydraulic brake system for proper operation. Refer to Hydraulic Brake System Diagnosis .

Did you find and correct the condition?

Go to Step 19

Go to Step 17

15

Replace the park brake relay A.

Did you complete the replacement?

Go to Step 19

--

16

Replace the park brake relay B.

Did you complete the replacement?

Go to Step 19

--

17

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

Did you complete the replacement?

Go to Step 19

--

18

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 19

--

19

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2