GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Combination Valve


See Figures 1 and 2

The combination valve used on the large Buicks, Oldsmobiles and Pontiacs is a three-function valve. It serves as a metering valve, balance valve, and brake warning switch. There are two different valves, one manufactured by Bendix and one manufactured by Kelsey-Hayes. Both valves serve the same function and differ only in minor details. In any case, all combination valves are non-adjustable and must be replaced if they are found to be defective.


  1. Disconnect all the brake lines at the valve. Plug the lines to prevent contamination and loss of fluid.
  3. Disconnect the warning switch wiring connector from the valve switch terminal.
  5. Remove the attaching bolts and remove the valve.
  7. Install the valve and torque the brake lines to 20 ft. lbs. (27 Nm) using flare nut wrench only.
  9. Bleed the entire brake system after valve installation.

Click image to see an enlarged view

Fig. Fig. 1: Combination valve mounting; all models similar

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Fig. Fig. 2: Cutaway view of the Bendix combination valve