K 1500 Suburban 4WD V8-5.3L VIN Z Flex Fuel (2003)
Hydraulic Control Assembly - Antilock Brakes: Testing and Inspection
Brake Pressure Application Testing (W/JL4)
Antilock Brake System
Diagnostic Information and Procedures
Brake Pressure Application Testing (W/JL4)
Important: Before performing the following tests, perform all of the isolation valve tests described in the wheel isolation test procedure. A
malfunctioning isolation valve may cause pressure to be applied to multiple wheels, instead of to just one wheel as commanded. If the brake being tested
fails to apply, does not hold for the full 9 second period or releases slowly after the 9 second hold, the TC Isolation Valve Test has failed.
TC Isolation Valve Test Procedure
1. Turn OFF the ignition.
2. Disconnect the brake switch harness connector.
3. Raise the vehicle so that all four wheels are about 15 cm (6 in) off of the floor. Refer to Lifting and Jacking the Vehicle in General Information.
4. Ensure that the park brake is released.
5. Turn ON the ignition.
6. Ensure that the transmission is in neutral (N).
7. Select the VSES Special Functions menu on the scan tool.
8. Select either the Left Front Brake Apply or the Right Front Brake Apply, whichever wheel has the most convenient access for you.
9. Press the Apply key on the scan tool.
10. Listen for the precharge pump to activate for approximately 2 seconds.
11. Immediately verify brake activation at the wheel by attempting to turn the wheel by hand.
12. Continue attempting to turn the wheel by hand and ensure the wheel remains locked for 9 seconds after the precharge pump turns OFF.
13. Verify that the brake releases quickly when the 9 second pressure hold is terminated.
14. Select either the Left Rear Brake Apply or the Right Rear Brake Apply, whichever wheel has the most convenient access for you.
15. Repeat steps 11, 12 and 13 for the rear wheel being tested.
16. Turn OFF the ignition.
17. Reconnect the brake switch harness connector.
