Reviving My '91 S-15 Jimmy

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Jan 12, 2023 | 09:06 AM

#21

Walleye Hunter

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Joined: Jun 2020

Posts: 339

Walleye Hunter will become famous soon enough

Quote:

Originally Posted by mr.vls

Is the Cruise Control mounted on the fender with a vacuum hose and electrical connector? You can test the vacuum side with a vacuum pump and apply vacuum directly to the Cruise control unit. It should hold vacuum without leaking. The vacuum hose from the cruise control goes a brake pedal switch that holds vacuum until you press the brake pedal. Apply vacuum to the hose from the cruise control side and it should hold vacuum until the brake pedal is pressed. The failure is most likely a bad vacuum hose or a leaking diaphragm inside the cruise control unit. Or the adjustment of the brake pedal switch.

OK, thanks. I have a MightyVac coming today or tomorrow and I can start hunting for vacuum leaks. What does the vacuum pump on the CC do? I would expect all vacuum to come off of the manifold.

Jan 12, 2023 | 04:54 PM

#22

mr.vls

Super Member

Joined: Apr 2008

Posts: 1,346

There are 3 vacuum ports on the CC. One is the source from the engine and one is for the brake release switch. The brake switch hose should hold vaccuum. You can make sue you have vacuum to the switch.