Vacuum Vent Valve: Testing and Inspection

NOTE: The speed control dump valve located above the brake pedal on the brake bracket.







The speed control dump valve releases vacuum in the speed control servo whenever the brake pedal is depressed. The speed control dump valve serves as an extra safety feature. The speed control dump valve should be checked whenever brake application does not disengage the speed control system.

1. Disconnect the speed control dump valve-to-servo vacuum hose (with the yellow stripe) at the speed control servo.
2. Connect a Rotunda Vacuum Tester 014-R1058, or equivalent, to the end of the hose at the speed control servo.
3. Pump up the vacuum to approximately 33-50 kPa (10-15 inches).

NOTE: If vacuum cannot be obtained, check the hose and speed control dump valve for leaks. Repair or replace as necessary.

4. Depress the brake pedal. The vacuum should release.
5. If the speed control dump valve does not operate as specified, adjust or replace the speed control dump valve. Otherwise, return to the Pinpoint Tests. Pinpoint Tests