Service Procedure

1. Open hood and inspect pressure switch. If the current pressure switch terminal body is GRAY, move on to Step 2. If the current switch terminal body is BLACK, place a fender cover on the left fender, then remove and replace pressure switch according to the procedure below and then move on to Step 2.

a. Depressurize Powermaster unit by turning ignition "OFF", and apply and release brake pedal a minimum of ten (10) times using approximately fifty (50) pounds of force on pedal to fully deplete the power assist.

NOTICE:
FAILURE TO FULLY DEPRESSURIZE POWERMASTER UNIT COULD RESULT IN BRAKE FLUID BEING SPRAYED ON SERVICE PERSONNEL AND COULD CAUSE DAMAGE TO PAINTED SURFACES.

b. Disconnect 3-wire electrical connector (Figure 1, 40) from pressure switch (Figure 1, 1).

c. Remove old pressure switch (Figure 1, 1) and O-ring (Figure 1,2). Take care not to drip brake fluid on painted surface.

d. Lubricate new O-ring in Pressure Switch Kit (P/N 18018141) (Figure 1, 2) with clean, fresh brake fluid (DOT # 3) and install on new pressure switch below O-ring already installed in a groove on the pressure switch.

e. Install new pressure switch (Figure 1, 1) torque to 20-27 N-m (15-20 lb.ft.)

NOTICE:
TORQUE VALUES SPECIFIED ARE FOR DRY, UNLUBRICATED FASTENERS.

f. Reconnect 3-wire electrical connector (Figure 1, 40) to pressure switch (Figure 1, 1). Be sure electrical connector is securely seated.

IMPORTANT:
COMBINATION VALVE INSPECTION AND REPLACEMENT PROCEDURE IN STEP 2 APPLIES ONLY TO THE 1986 LESABRE AND ELECTRA ESTATE WAGON. FOR ALL OTHER VEHICLES, PROCEED TO STEP 3.


2. On Estate Wagon only, locate combination valve (on frame rail below master cylinder). If the current combination valve is Cast Iron, the valve must be replaced with a Brass valve by following the procedure below. If the vehicle already has the Brass valve, the combination valve does not need to be replaced. Proceed to Step 3. Figure 2 on the next page illustrates the differences in the two valves.

a. Remove the electrical warning harness connector from the pressure differential switch by squeezing the elliptical-shaped plastic lock ring and pulling up. A pair of pliers may aid in removing the connector.

b. Disconnect hydraulic lines at combination valve. Plug lines to prevent loss of fluid and entrance of dirt.

c. Remove cast iron combination valve.

d. Install brass combination valve. Torque mounting bolts to 20 N-m (14 lb.ft.)

e. Remove plugs and connect hydraulic lines at combination valve. Torque hydraulic fittings to 24 N-m (18 lb.ft.)

f. Connect electrical warning harness connector to pressure control differential switch.

g. Bleed entire brake system. Do not move vehicle until a firm brake pedal is obtained.

h. Check brake lines for proper clearances.


3. Install Campaign Identification Label.