GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C-Series Medium Duty Truck C6/C7/C8 🢒 DTC 🢒 DTC 009

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 adequate increase in system pressure when the pump motor is ON.

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

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 Park Brake Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Park Brake

2

Visually inspect the system for any signs of external fluid leaks.

Did you find and correct the condition?

Go to Step 8

Go to Step 3

3
  1. Disconnect the park brake pressure solenoid valve.
  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 4

4

Test the park brake pressure valve solenoid 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 5

5

CAUTION:: This system operates using fluid pressure up to 12 400 kPa (1800 psi). Some malfunctions can cause this pressure to be trapped in the system. Use caution when loosening pipe fittings on a system that does not work or personal injury can result.

  1. Reconnect the park brake pressure solenoid valve.
  2. Engage the park brake.
  3. Remove the pipe fitting from the park brake pressure solenoid valve to the park brake pump motor assembly.
  4. Observe the pipe fitting while disengaging the park brake.

Does any fluid leak out of the fitting?

Go to Step 6

Go to Step 7

6

Replace the park brake pressure solenoid valve. Refer to Park Brake Solenoid Valve Replacement .

Did you complete the repair?

Go to Step 8

--

7

Replace the park brake pump motor assembly. Refer to Park Brake Pump Replacement .

Did you complete the repair?

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