Mode F4: ABS Tests

This mode performs functional tests on the ABS system which help verify proper system operation. Error conditions can be further identified by testing and observing test results. In the "ABS TESTS" mode the following test can be performed:

1. Solenoid Valve-Pressure Reduction: This test indicates whether specific solenoid valves in the hydraulic modulator release pressure to assigned hydraulic wheel circuits.
2. Solenoid Valve-Hold Pressure: This test indicates whether specific solenoid valves in the hydraulic modulator hold pressure in assigned hydraulic wheel circuits.
3. AUTO Test: This test cycles each solenoid valve and operates the pump motor briefly. The EBCM will store a diagnostic trouble code if test conditions fail.

The "PRESSURE REDUCE" test activates a selected hydraulic wheel circuit valve, placing it in the pressure reduce position. Valve action can then be verified by checking the appropriate wheel for proper brake action. The TECH 1 will indicate whether the valve action was commanded properly. This test used in conjunction with the "PRESSURE HOLD" test, completely checks each solenoid valve. With the aid of an assistant, perform the following procedure.

1. Have assistant press brake pedal.
2. Set TECH 1 to command "PRESSURE REDUCE" mode.
3. Try to spin wheel being tested; wheel should spin due to reduced pressure signal.

The "PRESSURE HOLD" test activates a selected hydraulic wheel circuit valve, placing it in the pressure hold position. Valve action can then be verified by checking the appropriate wheel for proper brake action. The TECH 1 will indicate whether the valve action was commanded properly. This test used in conjunction with the "PRESSURE REDUCE" test, completely checks each solenoid valve. With the aid of an assistant, perform the following procedure.

1. Spin wheel freely, then set TECH 1 to command "PRESSURE HOLD."
2. Have assistant press brake pedal.
3. Try to spin wheel being tested; wheel should be free to spin due to hold command, even though brake is applied.