Cadillac: Cruise Control Problem, vacuum problem, vacuum switch

Question

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Followup To

Question -
'87 Coupe DeVille. I have a recurring problem with the CC. No codes. The switch-test shows them working properly. The problem occurs when I either turn the engine Off or disconnect with the brake pedal. What happens is that it won't hold a steady throttle afterwards. Upon 'resume' it gets back to speed, then immediately throttles back. This action keeps up until I turn the CC Off. Turning it back On (at the CC switch), only continues the behavior. Prior to that it works perfectly. Could this be an electrical input/output problem with the VSS? What is confusing me is why it works properly when I first turn it on, then it doesn't. Might there be a vacuum problem? Thanks for any info.....

Answer -
Most likely a vacuum switch problem at the vacuum switch at the brake pedal.

OK....what is the best way to diagnose the vacuum sw at the brake pedal?  Thanks, I appreciate the help.

Answer
You will need to contact me at:


tomcjoy@msn.com


In order for me to provide you with pictures and and electrical schematic to find and fix your problem since this board does not allow sending pictures.

PLEASE include your original question(s) and the MAKE-MODEL-YEAR and ENGINE SIZE of your vehicle when you contact me.

PLEASE tell me if you do your own repairs and or your skill level of auto repair. This is VERY VERY important if I am to be able to help you repair your own vehicle .