Valve Solenoid-Pressure Hold Test

The Pressure Hold Mode activates the selected wheel circuit Inlet valve, placing the valve in the pressure hold position. When the valve is in the pressure hold position, the valve will not allow the master cylinder to deliver pressure to the hydraulic wheel circuit. This is done under actual operating conditions because the Electronic Brake Control Module/Electronic Brake Traction Control Module (EBCM/EBTCM) determines that the wheel is moving too slowly. The master cylinder pressure is held from the wheel in order to allow the wheel to rotate at an appropriate speed. The Scan Tool commands the valve to close. This should allow the technician to spin the wheel, even though an assistant is applying the brake pedal. Complete the following steps in order to perform the test:
1. Turn the ignition switch to the OFF position.
2. Install the scan tool.
3. Turn the ignition switch to the RUN position.
4. Place the transmission in (N) Neutral.
5. Raise the vehicle until the wheels are six inches from the floor.
6. Select the Valve Solenoid Test.
7. Have an assistant command Hold Pressure with the scan tool.
8. Have the assistant press and hold the brake pedal.
9. Attempt to move the test wheel by hand.
^ The wheel should move even though the assistant is applying the brake pedal.
^ The front wheels may be difficult to move by hand, but can be turned if the system is working properly.