Brake Proportioning/Combination Valve: Service and Repair

REMOVAL PROCEDURE

Important: Note the identification code on the combination valve. The new valve must have the same identification number as the old valve.

CAUTION: Before removing or installing any electrical unit or when a tool or equipment could easily come in contact with "live" exposed electrical terminals, disconnect the negative battery cable to help prevent personal injury and/or damage to the vehicle or components. Unless instructed otherwise, the ignition switch must be in the "OFF" or "LOCK" position.

1. Disconnect the negative battery cable.
2. Raise the vehicle.
3. Support the vehicle with safety stands.
4. Remove the Electro-Hydraulic Control Unit (EHCU) splash shield.
5. Remove the combination valve electrical connector.
6. Remove the front and the rear brake pipes.
7. Remove the three bolts securing combination valve to the Brake Pressure Modulator Valve (BPMV) (11).
8. Remove the combination valve from the BPMV (12).
9. Remove the two transfer tubes (13).





INSTALLATION PROCEDURE

Important:
^ Verify that the replacement combination valve has the same pin punched identification code as the code on the old combination valve.
^ Do not reuse the transfer tubes. Always install new transfer tubes with the new combination valve.

1. Install the two new transfer tubes into the combination valve until fully seated (13).
2. Install the combination valve to BPMV (12).

NOTICE: Always use the correct fastener in the proper location. When you replace a fastener, use ONLY the exact part number for that application. The manufacturer will call out those fasteners that require a replacement after removal. The manufacturer will also call out the fasteners that require thread lockers or thread sealant. UNLESS OTHERWISE SPECIFIED, do not use supplemental coatings (paints, greases, or other corrosion inhibitors) on threaded fasteners or fastener joint interfaces. Generally, such coatings adversely affect the fastener torque and joint clamping force, and may damage the fastener. When you install fasteners, use the correct tightening sequence and specifications. Following these instructions can help you avoid damage to parts and systems.

3. Install the three combination valve bolts (11).
^ Tighten the bolts first to 8 Nm (6 ft. lbs.), then to 16 Nm (12 ft. lbs.).

4. Install the front and the rear brake pipes to the combination valve.
^ Tighten the brake pipe fittings to 24 Nm (18 ft. lbs.).

5. Connect the combination valve electrical connector.
6. Install the EHCU splash shield.
^ Tighten the splash shield bolts to 16 Nm (12 ft. lbs.).

7. Remove the safety stands.
8. Lower the vehicle.
9. Connect the negative battery cable.

Important: Verify that the combination valve metering rod is depressed during bleeding.

10. Bleed the brake system.