(B)ABS System Functional Check

Figure 12 - Testing Wheel Rotation:

Test Description: While manually operating the system, this test determines whether the system applies braking force to all the wheels and allows the wheels to rotate when ABS calls for a release of brake pressure.
Symptoms: Wheel lock during braking, vehicle pulls to one side.
Possible Causes: Caliper or parking brake stuck, low or no boost pressure, master cylinder malfunction, solenoid malfunction, loose or damaged wires or connectors.

Inspect

1. Properly connect 94-00101-A to vehicle
2. Have an assistant sit in the driver's seat (or use a brake pedal actuator) to operate the brakes and 94-00101-A during the following procedures.
3. Raise vehicle and suitably support, refer to GENERAL INFORMATION(SECTION 0A).
4. Turn ignition on. Put transaxle in neutral. Do NOT apply brakes. Try to rotate each wheel (Figure 12). If all wheels do not rotate, check operation of the parking brake and brake calipers.

Important

^ The rear wheels should turn with little or no resistance. However, the front wheels will have some resistance to rotation caused by the driveline and differential. This resistance on the front wheels is normal. During this test, "no wheel rotation" exists when a wheel cannot be turned using hand force.
5. Apply medium pressure to the brakes. Again try to rotate each wheel. All wheels should not rotate.
6. If either of the front wheels rotate
a. Bleed system, refer to "Powermaster III Bleeding" in this section, repeat steps 2 through 6.
b. While depressing brake pedal, if brake fluid being forcefully sprayed into the reservoir can be heard, replace the solenoid associated with the test wheel.
c. While depressing brake pedal, if brake fluid being forcefully sprayed into the reservoir is not heard, or step 6(b) does not correct problem, replace Powermaster III Unit, refer to "Powermaster III Unit" in this section.
7. If the rear wheels rotate, a low or no boost pressure condition exists, refer to test (D) "Low or No Boost Pressure Check" in this section.
8. Have an assistant apply the service brake pedal moderately, and using 94-00101-A, energize both the hold and release solenoids for a specific wheel. 94-00008-A utilizes "Release Function" in ABS hydraulic function check menu of 94-00101-A. Test wheel rotation for the appropriate solenoid. Also, listen for the sound of fluid being forcefully sprayed in the reservoir, note pedal travel and note whether the pump runs constantly or at frequent intervals while the solenoids are energized. Test other hold and release solenoids in the same way.

Important

^ During this test, the Powermaster III will not reduce front brake line pressure to zero psi. Approximately 10 psi will be left in the front brake lines under these conditions. Therefore, some drag may be noticed when testing wheel rotation. This drag is normal and should not be confused with a wheel that does not rotate (cannot be turned with hand force).
9. While performing the release function for a specific wheel, the respective wheel should rotate (Figure 12). While the solenoids are energized, you should not hear the sound of fluid being forcefully sprayed in the reservoir, the brake pedal should not steadily sink to the floor and the pump should not run constantly or frequently.
10. While the solenoids are energized, if a wheel does not rotate, fluid sprays forcefully in the reservoir, the brake pedal sinks steadily to the floor or the pump runs unacceptably, check the wiring and connections to the appropriate solenoid carefully for crossed wiring. If necessary, replace the Powermaster III wiring harness if any of the wires or connections to the appropriate solenoid are damaged. Perform steps 8 through 10 again.
11. If any of the conditions listed in step 10 continues to occur, replace the respective solenoid and perform steps 8 through 10 again.
12. If any of the conditions listed in step 10 still continues to occur, replace the Powermaster III Unit.