Proportioning Valve Testing

Fig. 24 Type 1, Combination Valve Pressure Gauge Test Connections:

1. Install gauge set with T-fitting No. C-4007A, as shown. Special adapter tubes may be fabricated from a short piece of brake tube, a 9/16 X 18 tube nut, and a 3/8 X 24 tube nut.
2. Bleed the hose and gauge set.
3. While watching pressure gauges, have an assistant depress the brake pedal. Note gauge readings, then refer to Brakes and Traction Control/Brakes/Specifications/Mechanical.
4. If pressure readings are not as specified, replace the combination valve and note the following:
a. After installing a new combination valve, bleed the hydraulic brake system, refer to Brakes and Traction Control/Brakes/Service and Repair.
b. Upon completion of bleeding the hydraulic brake system, reset the brake warning switch by depressing the brake pedal with moderate force. The brake warning lamp will turn off when the switch is reset.