Service Procedure

Figure 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 termiial body is BLACK place a tender cover on the left tender, then remove and replace the pressure switch according to the procedure below. After that, move on to Step 2.

A. Depressurize the Powermaster unit by turning ignition "OFF", then 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.

CAUTION: Failure to fully depressurize the Powermaster unit could result in brake fluid being sprayed on service personnel and could cause damage to painted surfaces.

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

C. Remove the old pressure switch (Figure 1, 1). The original O-ring should be on the old pressure switch. If not, check Powermaster unit for the loose O-ring and remove it. Take care not to drip brake fluid on painted surfaces.

The old pressure switch has only one O-ring. Do NOT reuse the old O-ring,
D. Obtain new Pressure Switch (P/N 18018141). The new pressure switch has an O-ring already installed in a groove on h. A second O-ring should be found loose in the box with the switch.
Lubricate the second O-ring (Figure 1, 2) with clean, fresh brake fluid (DOT # 3) and install in a groove between the threads and the existing O-ring on the new pressure switch.

E. Install new Pressure Switch (Figure 1, 1) and torque to 24 N-m (18 lbs.ft.)

NOTE: Torque values specified are for dry, unlubricated fasteners.

F. Reconnect 3-wire electricai connector (Figure 1, 40) to Pressure Switch (Figure 1, 1). Be sure electrical connector is securely seated,

Figure 2:

2. 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 illustrates the differences in the two valves,

A. Remove the electrical wiring harness connector from the pressure differential switch by squeezing the eliptical-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 lbs.ft.).

E. Remove plugs and connect hydraulic lines at Combination Valve. Torque hydraulic fittings to 24 N-m (18 lbs.ft.).

F. Connect electrical wiring harness connector to pressure control differential switch.

G. Bleed entire brake system following the procedure in section 5D4 of the 1986 Oldsmobile Cutlass Supreme, Cutlass Saloon, Custom Cruiser Chassis Service Manual. Do not move vehicle until a firm brake pedal is obtained.

H. Check brake lines for proper clearance.