Hydraulic Control Test

This test is used to verify base brake apply and ABS release, hold, and apply functions. During testing, if a problem is encountered, the scan tool will provide information on the problem.
1. Turn the ignition switch to the OFF position.
2. Raise the vehicle such that all wheels to be tested are off the ground.
3. Install scan tool.
4. Turn the ignition switch to RUN.
5. Select MISC. TESTS, HYDRAULIC CONTROL.
6. Select the channel to be tested. When testing the rear brakes, both rear wheels should rotate and not rotate together at the various points in the test, this is true because both rear brake pressures are controlled together.
7. Firmly depress brake pedal. Pedal should remain high and firm.
8. Have an assistant attempt to rotate the wheel being tested. If the wheel does not rotate, base brake apply is working properly.
9. With the brake pedal still depressed, press the up arrow key on the scan tool to start the test. The brake pedal should remain high and firm (if the brake pedal moves toward the floor, verify the solenoid electrical connectors are connected to the correct solenoids).
10. With the brake pedal still depressed, have the assistant attempt to rotate the wheel. The wheel should rotate with little or no resistance for the full 18 seconds of the test.
11. After 18 seconds, brake pressure will be applied and a slight bump may be felt in the pedal. This is normal. The assistant should not be able to rotate the wheel at this point.