Hydraulic Control Assembly - Antilock Brakes: Testing and Inspection

Hydraulic Assembly Internal Leak Test

Fig. 65 Gauge Tool Installed:

Fig. 66 Hydraulic Assembly Accumulator Port Plug Location:

Fig. 67 Pressure Gauge And Adapter Installation:

If an internal leak is suspected in the ABS hydraulic circuit an ABS test gauge special tool No. 6685 has been developed to assist in diagnostics. This fixture will assist in determining if there is an internal leak and if the leak is in the hydraulic unit of the pump motor assembly. It can be used whether the pump shuts off or not.
Use the following procedure to install and use the test gauge when the diagnostic charts indicate.

1. De-pressurize the accumulator by pumping the brake pedal 40 times or more with the ignition switch in the Off position.
2. Remove hydraulic assembly wiring harness connector from dual pressure switch on bottom of hydraulic assembly. Connect wiring harness from test gauge tool into disconnected wiring harness connector.
3. Locate and remove high pressure brake fluid hose off of the hydraulic assembly from the pump/motor.
4. Ensure valve is in the open position on the test gauge tool then install tool into high pressure hose opening. Torque nut to 145 inch lbs.
5. Install high pressure brake fluid hose into test gauge tool and torque tube nut to 145 inch lbs.
6. Remove hydraulic assembly accumulator port plug.
7. Install pressure gauge adapter tool No. MST-6491A into accumulator port of hydraulic assembly. Torque adapter to 7.5 ft. lbs.
8. Connect pressure tester tool No. MST-6163 and hose adapter tool No. MST-6505 onto adapter in accumulator port. Ensure retaining clip is installed on the adapter before re-pressurizing the hydraulic unit.
9. Run the required diagnostic procedure and make repairs as necessary.
10. After procedure is complete, proceed as follows:
a. De-pressurize system and remove all special tools.
b. Install accumulator port plug and torque to 9 ft. lbs.
c. Install high pressure brake hose and torque tube nut to 145 inch lbs.
d. Connect hydraulic assembly wiring harness connector on top of the dual pressure switch. Ensure lock on connector is fully engaged with tab on dual function pressure switch.
e. Re-pressurize system and check for leaks.
f. De-pressurize system and check brake fluid level in hydraulic assembly reservoir. Fill if required.