Hydraulic System: Description and Operation

FLUID AND FLUID HANDLING

CAUTION: Brake fluid may be irritating to the skin or eyes. In case of contact, take the following actions:
^ Eye contact - rinse eyes thoroughly with water.
^ Skin contact - wash skin with soap and water.

NOTICE: Brake fluid will damage electrical
connections and painted surfaces. Use shop cloths, suitable containers, and fender covers to prevent brake fluid from contacting these areas. Always re-seal and wipe off brake fluid containers immediately after use to prevent spills. Use Delco Supreme 11 Brake Fluid GM P/N 1052535 or an equivalent DOT-3 motor vehicle brake fluid. Brake fluid should always be stored in a closed, sealed container. Never use previously opened containers of stored brake fluid. Always use new fluid from a sealed container. Brake fluid left in an open or improperly sealed container will absorb moisture. This can lower the fluid's boiling point and result in system contamination, corrosion, or deterioration of rubber components.

SUBSTANDARD OR CONTAMINATED BRAKE FLUID
Improper fluid, water, or any other contaminants in the brake fluid may cause the brake fluid to boil or deteriorate rubber components in the hydraulic system.

Swollen master cylinder piston seals show that rubber deterioration has occurred. Deterioration may also be shown by swollen wheel cylinder boots, caliper boots, or the master cylinder reservoir diaphragm.

If rubber deterioration is found, replace all rubber parts in the system, including the hoses. Also check for fluid on the brake linings. If any is found, replace the linings.
If the fluid is contaminated and the master cylinder piston seals are satisfactory, check for leaks or excessive heat conditions. If no leaks or excessive heat conditions are found, flush the system.

FLUSHING THE SYSTEM
Flushing the brake hydraulic system involves running new brake fluid through the system until the fluid at each bleeder valve comes out clear. This is the only way to clean contaminated fluid out of the system.

COMBINATION VALVE
The combination valve is an integral part of the Antilock Brake System (ABS).

STOPLAMP SWITCH
The zero adjust stoplamp switch design eliminates the need for stoplamp switch adjustment because the switch is installed along with the brake push rod and held by a single retainer.

WARNING/INDICATOR LAMP OPERATION
"BRAKE" Lamp
The "BRAKE" warning lamp in the instrument cluster warns the driver of either a loss of hydraulic fluid pressure, parking brake operation, or a possible malfunction in the antilock brake system. The "BRAKE" lamp will illuminate when ground is supplied from either the combination valve switch, parking brake switch, or Brake Pressure Modulator Valve (BPMV).