The combination valve contains a pressure differential valve and switch and a proportioning valve. The pressure differential switch is connected to the brake warning lamp and monitors fluid pressure in the separate front/rear hydraulic circuits. The proportioning valve is used to balance front-rear brake action at high decelerations when a percentage of the rear weight is transferred to the front wheels. The valve allows normal fluid pressure during moderate braking.
Removal & Installation
The unit is not serviceable. If it fails, it must be replaced.
- Disconnect the wiring at the valve.
- Place a container beneath the valve before loosening the fittings.
- Disconnect the brake lines using a flare nut wrench on the fittings.
- Remove the valve mounting hardware and take off the valve.
- Reverse the removal procedure.
- Start the brake line fittings by hand. Move the lines as necessary to make sure the fittings engage the threads correctly. If resistance is felt, back them off and try again. Do NOT put a wrench on the fittings until you are sure they are correctly threaded.
- Tighten the line fittings to 14 ft. lbs. (19 Nm). Do NOT overtighten. Do NOT attempt to stop leaks by overtightening the fittings. This is unlikely to help.
- Add new fluid and bleed the brake system.