MASTER CYLINDER

GENERAL INFORMATION

The tandem master cylinder (Fig. 1) has a glass reinforced nylon reservoir and an anodized aluminum body.

Do not hone the bore of the cylinder, as this will remove the anodized surface.

The reservoir is indexed to prevent installation in the wrong direction (Fig. 2). The cap diaphragms are slit to allow atmospheric pressure to equalize on both sides of the diaphragm.

The primary and secondary outlet tubes from the master cylinder are connected to the valve mounted under the master cylinder. The front part of this block connects to the secondary outlet tube and supplies the right rear and left front brakes. The rear portion of the block connects to the primary outlet tube and supplies the right front and left rear brakes.

To check the operation of the Brake Fluid Level sensor, with ignition on and wiring still attache- d,remove sensor from master cylinder and hold in upright position. Within 30 seconds the instrument panel message BRAKE FLUID LOW should appear. Next invert the sensor. The instrument panel message should turn off immediately. If the above sequence occurs the sensor is operating properly. If the message does not appear remove the wiring from the sensor and using a jumper wire connect both sides of the plug. The instrumental panel message BRAKE FLUID LOW should appear within 30 seconds. If the message does not appear a problem exists in the wiring or instrumentation. If the message does appear the sensor is faulty and must be replaced. The

Brake Fluid Level sensor is not a repairable item (Fig. 2).

Fig. 1 Aluminum Master Cylinder (Cutaway View)

BRAKE FLUID LEVEL SENSOR

The Brake Fluid Level sensor is found only in the AG body vehicles with the visual electronic message center. The purpose of the sensor is to provide the driver with an early warning message that the brake fluid in the master cylinder reservoir has dropped to a below normal level.

As the fluid drops below the design level the sensor closes the warning message circuit. Approximately 15 seconds later the message BRAKE FLUID LOW appears on the instrument panel. At this time the master cylinder reservoir should be checked and filled to the bottom of the rings with DOT 3 brake fluid.

Fig. 2 Brake Fluid Level Sensor

TESTING THE MASTER CYLINDER

Be sure master cylinder vents at both ports.

Apply pedal lightly with engine running and look for fluid squirting or swirling into reservoirs.

In this master cylinder, a special baffle reduces the amount of fluid entering the secondary reservoir only a small disturbance may be seen.