Valve Solenoid-Pressure Release Test

The Pressure Release Mode activates the selected wheel circuit Outlet valve, placing the valve in the pressure release position. When the Outlet valve is in the pressure release position, the valve allows the wheel caliper pressure to be returned to the master cylinder. 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 by closing the Inlet valve and pressure is released by opening the Outlet valve. This allows the wheel to rotate at an appropriate speed. The scan tool commands the Inlet valve to close and the Outlet valve to open. 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. Have the assistant press and hold the brake pedal.
7. Select the Valve Solenoid Test.
8. Have an assistant command Release Pressure with the scan tool.
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.