Cruise Control, I already read all the posts!!!!

[mnmasotto]

I have read all the posts! They were helpful but did not answer my question.

I have a 1987 Carrera. Up until a week ago my cruise control was working perfectly. Now it does not work at all. I did the tests with a multimeter in the Bentley manual. The failed tests point to: 1) bad clutch switch 2) bad brake switch 3) Bad number 6 fuse.

I checked the fuse and it is fine. I even cleaned off the contacts at the fuse box. I tested the clutch switch and it appears to be working fine. I do not know where the brake switch is and if you can test it?

Does this sound familiar to anyone? Could a bad cruise control brain box be the culprit? I was about to send it to Beckman Industries for a test and rebuild.

Again, I have read all the posts I could find. They were very helpful in getting me started in the diagnosis process but I am stuck here. Help me Obiwan!

[wente]

My 87' cruise control failed last year with many of the same symptoms. It turned out to be due to the third brake light bulb being burnt out. The cruise brain is apparently wired into that circuit... The brain sees +12v through the bulb filament when the pedal is up, and sees it go to ground when the pedal switch closes. Without a good filament in the bulb, it sees an open circuit and presumably thinks you have your foot on the brake, so it refuses to work. Took me a few weeks to find that one!

[Brorag]

I've got an 87 also:

• cruise stopped working for ~18 months
• I cleaned all the connectors in the circuit & that fixed it
• Recently removed the 3rd stop light to paint car and the cruise still works

go figure.................

[mnmasotto]

I just replaced the third brake light. I checked it last night adn it is working.

I also cleaned all the electrical contact points.

Thanks for the help, Mark