With Antilock Brakes

Proportioning Valve Location On Hydraulic Control Unit:

Proportioning Valve Installation For Pressure Testing:

Pressure Gauges Installed On Pressure Test Fittings At Hydraulic Control Unit:

PROCEDURE
1. Road test vehicle to verify premature rear wheel Antilock Brake System (ABS) cycling, to determine which proportioning valve needs to be tested.
2. Remove hydraulic brake tube from one of the proportioning valves.
3. Then remove proportioning valve from that outlet port of the Hydraulic Control Unit HCU.

CAUTION: Be sure the pressure test fitting being installed into the HCU, has the correct thread sizes for installation into the HCU and installation of the proportioning valve.

4. Install Pressure Test Fitting, Special Tool 6805-1 or 6805-2, or equivalents into the outlet port of the HCU.
5. Install proportioning valve into pressure test fitting installed in the HCU outlet port.

CAUTION: Be sure the pressure test fitting being installed into proportioning valve, has the correct thread sizes for installation into the proportioning valve and installation of brake tube fitting into proportioning valve.

6. Install Pressure Test Fitting, Special Tool 6805-3 or 6805-4, or equivalents into the outlet of the proportioning valve.
7. Connect brake tube onto pressure test fitting installed in proportioning valve.
8. Install a Pressure Gauge, Special Tool C-4007-A, or equivalent into each pressure test fitting. Bleed air out of hose from pressure test fitting to pressure gauge, at pressure gauge to remove all trapped air.
9. With the aid of a helper, apply pressure to the brake pedal until reading on proportioning valve inlet gauge, is at the pressure shown on the following chart. Then check the pressure reading on the proportioning valve outlet gauge. If proportioning valve outlet pressure does not agree with value shown on the following chart, when inlet pressure shown on chart is obtained, replace the proportioning valve. If proportioning valve is within pressure specifications do not replace proportioning valve.
10. Install proportioning valve in HCU and hand tighten until proportioning is fully installed and 0-ring seal is seated into HCU. Then torque proportioning valve to 40 Nm (30 ft. lbs.).
11. Install brake tube on proportioning valve. Torque tube nut to 17 Nm (145 in. lbs.).
12. Bleed the affected brake line. See Bleeding Brake System in the Service Adjustments section of the manual for proper bleeding procedure.
13. Repeat steps 2 through 12 for the second proportioning valve.
14. Check rear wheel brake shoe linings for contamination or for replacement brake shoes not meeting OEM brake lining material specifications. These conditions can also be a possible cause for a premature rear wheel skid.