For 1990-2009 cars

### Circuit Description

In order to release the parking brake, the pump motor must supply fluid pressure to the actuator. When this pressure overcomes the spring tension inside of the actuator, the actuator piston moves, releasing the parking brake. The park brake pressure sensor monitors the fluid pressure whenever the ignition is ON.

### Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:

• | Testing for Electrical Intermittents

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

• | Connector Repairs

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Park Brake System Schematics
1 | Did you perform the Parking Brake Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Park Brake
2 |

1. Block the drive wheels in order to ensure the vehicle does not roll when the parking brake is released.
2. Ensure the parking brake is applied.
3. Turn ON the ignition.
4. Release the parking brake.
5. Reapply the parking brake.

Does the parking brake pump motor turn OFF?

Go to Diagnostic Aids

Go to Step 3

3 | Disconnect the park brake pump motor relay harness connector. Does the parking brake pump motor turn OFF? | Go to Step 5 | Go to Step 4
4 | Repair the short to voltage in the park brake motor supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 9 | --
5 | Connect a test lamp between the park brake motor relay control circuit and a good ground. Does the test lamp illuminate? | Go to Step 6 | Go to Step 7
6 |

1. Disconnect from the PBCM, the harness connector containing the park brake motor relay control circuit.
2. Test the park brake motor relay 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 9

Go to Step 8

7 | Replace the park brake pump motor relay. Refer to Park Brake Pump Relay Replacement . Did you complete the replacement? | Go to Step 9 | --
8 | Replace the PBCM. Refer to Park Brake Control Module Replacement . Did you complete the replacement? | Go to Step 9 | --
9 | Apply the parking brake. Does the parking brake pump motor turn OFF? | System OK | Go to Step 3