Brake Fluid Pump: Service and Repair

WARNING: To help avoid personal injury due to a retained load on the hydraulic modulator/motor pack assembly, and to prevent setting Diagnostic Trouble Codes (DTCs), the Gear Tension Relief function of the Tech 2, or equivalent scan tool, must be performed prior to removal of the hydraulic modulator.

CAUTION: The following service procedures shall be performed only after the hydraulic modulator/motor pack assembly has been removed from the vehicle. Do not perform these procedures with the unit installed on the vehicle.

NOTE: Complete overhaul of the hydraulic modulator is not authorized only the following steps. These steps will break the unit down into major components for replacement purposes.

Hydraulic Modulator/Motor Pack Assembly:

REMOVE OR DISCONNECT
1. Six Torx (R) head screws and gear cover from hydraulic modulator/motor pack assembly.
2. Four Torx (R) head screws and motor pack from hydraulic modulator.

CAUTION:
^ Use care when handling motor pack to ensure motor pack connector is not damaged, or accidental intrusion of brake fluid into the motor pack does not occur. This may result in a premature failure of the motor pack.
^ Take care in handling the motor pack. If dropped or damaged during handling, the motor pack must be replaced.
^ If disassembly of the hydraulic modulator was due to an ABS hydraulic functional test that did not pass, the Automated Motor Pack Diagnosis Test (function of the scan tool) should be performed at this time to isolate the motor pack or hydraulic modulator.

NOTE:
^ No repair of the motor pack is should be attempted. Replace as an assembly.

3. Three nuts and gears from hydraulic modulator.

CAUTION:
^ Do not allow gear to turn while removing the retaining nut, since the modulator piston can hit the top of the modulator bore, damaging the piston.
^ Turn the modulator gear to position the piston in the center of its travel. Place a screwdriver through the holes in the gears (not between the gears) into the recessed hole in the modulator base. This will prevent the gear from turning, aiding in gear removal.

INSTALL OR CONNECT
1. Gears to hydraulic modulator secure each gear with one nut, then tighten to 8.5 Nm (76 inch lbs.).

Gear Positioning:

2. With the hydraulic modulator upside down, and the gears facing you, rotate each gear counterclockwise until movement stops. This procedure will position the pistons very close to the top of the hydraulic modulator bore, simplifying the brake bleeding procedure.
3. Motor pack to hydraulic modulator, aligning the three motor pack gears with the modulator gears.

CAUTION:
^ Take care in handling the motor pack. If dropped or damaged during handling, the motor pack must be replaced.

4. Four Torx (R) head screws securing motor pack, then tighten to 5 Nm (44 inch lbs.).
5. Gear cover to hydraulic modulator/motor pack assembly, secure with six Torx (R) head screws, then tighten to 4 Nm (36 inch lbs.).