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Proportioning Valve

WARNING: This page is about a different car, the 1994 Plymouth Sundance, 1994 Plymouth Acclaim, 1994 Dodge Spirit, 1994 Dodge Shadow, and 1994 Chrysler LeBaron. However, it is still accessible from the selected car via links, so may be relevant.
  1. Rear wheel lock-up or skidding indicates faulty proportioning valve. See appropriate PROPORTIONING VALVE IDENTIFICATION table. Road test vehicle to determine which rear brake system is faulty.
  2. If right rear wheel skids first under hard braking condition, install pressure gauge and "T" fitting of Tester Set (C-4007-A) in line between master cylinder secondary inlet brakeline and control valve inlet. See Fig 1. Install second pressure gauge to right rear control valve outlet. Go to step 4).
  3. If left rear wheel skids first, install pressure gauges on opposite side of control valve. See Fig 2. Go to step 4).
  4. Bleed hoses and gauges. Have an assistant depress and hold pressure on brake pedal. Note and record pressure gauge readings. If inlet or outlet pressure readings DO NOT agree with specifications, replace control valve. See BRAKE PRESSURE table.
Fig 1: Connecting Gauges For Right Rear Skid Test
G90H00825Courtesy of CHRYSLER CORP.
Fig 2: Connecting Gauges For Left Rear Skid Test
G90I00826Courtesy of CHRYSLER CORP.
PROPORTIONING VALVE IDENTIFICATION (NON-ABS)

Body Application (1) Split/Slope Identification
AA 14" Wheel Disc/Drum 400 psi/.43 % YEL
AA 14" Wheel Disc/Disc 300 psi/.43 % TAN
AJ 14" Wheel Disc/Drum 400 psi/.43 % YEL
AP 14" Wheel Disc/Drum 400 psi/.43 % YEL
AP 14" Wheel Disc/Disc 500 psi/.27 % GRY
(1) Split point is when proportioning valve changes rear brake pressure to prevent skidding. Slope is the pressure differential (percentage ratio) between front and rear brakes.
NOTE: Vehicles equipped with ABS use a proportioning valve for each hydraulic circuit screwed directly into master cylinder ports.
PROPORTIONING VALVE IDENTIFICATION (ABS)

Body Code Application (1) Split/Slope
All 14" Wheel Disc/Disc 435 psi/.43 %
(1) Split point is when proportioning valve changes rear brake pressure to prevent skidding. Slope is the pressure differential (percentage ratio) between front and rear brakes.
BRAKE PRESSURE

Master Cylinder Pressure (1) Split/Slope Rear Brake Outlet Pressure
1000 psi 441 psi/.45 % 640-720 psi
1000 psi 515 psi/.45 % 685-765 psi
1000 psi 588 psi/.45 % 725-805 psi
1000 psi 662 psi/.45 % 765-845 psi
1000 psi 294 psi/.30 % 460-540 psi
1000 psi 368 psi/.30 % 510-590 psi
1000 psi 441 psi/.30 % 560-640 psi
(1) Split point is when proportioning valve changes rear brake pressure to prevent skidding. Slope is the pressure differential (percentage ratio) between front and rear brakes.
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