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.

### Conditions for Running the DTC

• | The ignition is ON.

• | The parking brake is being released.

### Conditions for Setting the DTC

The parking brake pressure sensor does not detect an increase in system pressure after 2 seconds of pump motor operation.

### Action Taken When the DTC Sets

• | The SERVICE PARK BRAKE indicator turns ON.

• | Electro-hydraulic park brake function may be disabled.

### Conditions for Clearing the DTC

The conditions for setting the DTC are no longer present and you use the procedure specified in Diagnostic Trouble Code (DTC) Clearing .

### Diagnostic Aids

DTC 001 may set during normal park brake operation in extremely cold weather. Low ambient temperatures cause the viscosity of the hydraulic fluid to increase, making the fluid reluctant to flow. Low system voltage may also cause this DTC to set due to low pump motor speed. The PBCM records system voltage when the DTC sets in order to aid in system diagnosis.

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Electrical Intermittents , Testing for Intermittent Conditions and Poor Connections , Wiring Repairs and Connector Repairs in Wiring Systems.

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

1. Cycle the park brake switch.
2. Observe the park brake pump motor operation.

Does the park brake pump motor run?

Go to Step 3

Go to Park Brake Pump Motor Does Not Run

3 | Check the actuator movement during park brake pump motor operation. Does the actuator extend normally? | Go to Park Brake Pressure Sensor Circuit Check | Go to Step 4
4 |

1. Cycle the park brake switch.
2. Verify that the park brake pressure solenoid valve clicks.

Does the solenoid click?

Go to DTC 009

Go to Step 5

5 |

1. Disconnect the park brake pressure solenoid valve connector.
2. Test the park brake pressure valve solenoid supply voltage circuit for an open. 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 | Use a DMM to test the ground circuit for an open. 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 park brake pressure solenoid valve. Refer to Park Brake Solenoid Valve Replacement . Is the repair complete? | Go to Step 8 | --
8 |

1. Reconnect all the connectors.
2. Clear DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing .
3. Operate the park brake.
4. Verify that no DTCs reset. Refer to Diagnostic Trouble Code (DTC) Displaying .

Did the same DTC reset?

Go to Step 2

Go to Step 9

9 | Did any DTCs reset? | Go to Diagnostic Trouble Code (DTC) List | System OK