Caravan FWD V6-201 3.3L VIN R MFI (1997)
Brake Proportioning/Combination Valve: Testing and Inspection
TEST PROCEDURE
On a vehicle equipped with ABS, premature or excessive rear wheel ABS cycling may be an indication that the brake fluid pressure to the rear
brakes is above the desired output. Prior to testing a proportioning valve for function, check that all tire pressures are correct. Also, ensure the
front and rear brake linings are in satisfactory condition. It is also necessary to verify that the brakes shoe assemblies on a vehicle being tested, are
either Original Equipment Manufacturers (OEM), or original replacement brake shoe assemblies meeting the OEM lining material specification.
The vehicles brake system is not balanced for after market brake shoe: assembly lining material. If brake shoe assembly lining material is of
satisfactory condition, and of the correct material specification, check for proper proportioning valve function using the following procedure.
Rear Brake Proportioning Valve And Brake Tube Locations
1. Road test vehicle to be sure the vehicle is truly exhibiting a condition of excessive rear wheel ABS cycling. Since ABS cycles both rear brakes
together both proportioning valves of the assembly must be tested. Use the following procedure to test the proportioning valve.
2. Remove one of the chassis brake lines coming from the ABS modulator, at the proportioning valve assembly.
3. Remove the hydraulic brake line going to one of the rear wheels of the vehicle from the proportioning valve.
4. Remove the 2 bolts attaching the proportioning valve to the frame rail.
CAUTION: When lowering the proportioning valve, care must be taken not to kink any of the chassis brake lines.
5. Carefully lower the proportioning valve for clearance to install the proportioning valve test fittings.
Proportioning Valve Test Fitting Installation
6. Install the required fitting from Pressure Test Fittings, Special Tool 6833, or equivalent into the inlet port of the proportioning valve assembly,
from which the chassis brake line was removed. Install the removed chassis brake line into the Pressure Test Fitting. Install the required fitting
from Pressure Test Fittings, Special Tool 6833, or equivalent into the required outlet port of the proportioning valve. Install the required fitting
from Pressure Test Fittings, Special Tool 6833, or equivalent into the required outlet port of the proportioning valve. Then install the removed
chassis brake line into the Pressure Test Fitting.
