Cruise Control Vacuum System, Checking

- Disconnect vacuum hose from vacuum pump.
- Push in vacuum servo unit diaphragm.
- Plug disconnected vacuum hose.
- Servo unit diaphragm must remain in and not move outward.

If the diaphragm returns (moves) to the starting position there is a leak in the vacuum system:
- Check the following:
- Cruise Control Brake Pedal Position (BPP) switch leaking or incorrectly adjusted; replace or adjust
- Vacuum servo unit leaking; replace
- Crack or split in vacuum hoses; replace