The in-line proportioning valves used on this vehi-
cle require special pressure fittings to test the pro-
portioning valves for proper proportioning valve
function. The pressure fittings are installed before
and after the proportioning valve being tested to ver-
ify proportioning valve is maintaining the required
hydraulic pressure to the rear wheel brake which it
controls.
The testing of proportioning valves for this vehicle,
if equipped with ABS, (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/PROPORTIONING
VALVE - DESCRIPTION).
PROPORTIONING VALVE TEST
The test procedure is the same for either rear pro-
portioning valve. After road testing the vehicle to
determine which wheel skids first, follow the proce-
dure below for testing the suspect proportioning
valve.
(1) Using a brake pedal holding tool as shown (Fig.
17), depress the brake pedal past its first one inch of
travel and hold it in this position. This will isolate
the master cylinder from the brake hydraulic system
and will not allow the brake fluid to drain out of the
master cylinder reservoir.
(2) Use the figure shown to determine which pro-
portioning valve needs to be tested (Fig. 16).
(3) Remove the hydraulic brake tube from the pro-
portioning valve controlling the rear wheel of the
vehicle that has premature wheel skid.
(4) Remove the proportioning valve from its outlet
port on the master cylinder.
CAUTION: Be sure the pressure test fittings being
installed into master cylinder and proportioning
valve, have the correct thread sizes needed.
(5) Install the Brake Pressure Adapters, Special
Tool 8644 and 6805-3 onto the proportioning valve
(Fig. 18).
(6) Install the proportioning valve (with tools) back
into the outlet port on the master cylinder.
(7) Attach a Pressure Gauge, Special Tool
C-4007-A, to each pressure adapter (Fig. 19).
(8) Remove the brake pedal holding tool. Bleed any
air out of the pressure gauge hoses at the pressure
gauge.
Fig. 16 Proportioning Valve Location
1 - RIGHT FRONT BRAKE TUBE
2 - LEFT FRONT BRAKE TUBE
3 - LEFT REAR BRAKE TUBE
4 - REAR PROPORTIONING VALVES
5 - RIGHT REAR BRAKE TUBE
Fig. 17 Brake Pedal Holding Tool
1 - CLUTCH PEDAL (IF EQUIPPED WITH MANUAL TRANSAXLE)
2 - THROTTLE PEDAL
3 - BRAKE PEDAL HOLDING TOOL
4 - STEERING WHEEL
5 - DRIVER’S SEAT
6 - BRAKE PEDAL
Fig. 18 Tools On Valve
1 - PROPORTIONING VALVE
PL BRAKES-BASE 5s - 17
PROPORTIONING VALVE (Continued)
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