See Figures 1 and 2
Since the introduction of the tandem master cylinders to the hydraulic brake system, a pressure differential warning signal has been added. This signal consists of a warning light on the dashboard activated by a differential pressure switch located below the master cylinder. The signal indicates a hydraulic pressure differential between the front and rear brakes of 80-20 psi (280-495 kPa), and should warn the driver that a hydraulic failure has occurred.
After repairing and bleeding any part of the hydraulic system, the warning light may remain on due to the pressure differential valve remaining in the off-center position. To centralize the valve, a pressure difference must be created in the opposite branch of the hydraulic system that was repaired or bled last.
VALVE CENTERING PROCEDURE
- Turn the ignition to either the ACC or ON position.
- Check the fluid level in the master cylinder reservoir. Fill to within 1 / 4 in. (6mm) of the top, if necessary.
- Depress the brake pedal firmly. The valve will centralize itself causing the brake warning light to go out.
- Turn the ignition OFF .
- Prior to driving the vehicle, check the operation of the brakes and obtain a firm pedal.