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Cadillac Repair/Electric Vacuum assist problem


1986 Cad. Coupe Deville Electric pump under battery case does not cycle off anytime key is on or engine running.This is a vacuum assist unit I believe for the brakes.can't find information from Cad. Dealer shops or wiring diagrams on internet. Any help would be great. Thanks,Gary


Not sure what you are referring to. To my knowledge, the only types of brake assist are hydro boost which are linked to the power steering or the brake vacuum booster located to the rear of the master cylinder. No familiar with any electric going to a brake assist, especially something that cycles. From your description I am wondering if you are referring to the air compressor for the rear suspension.

My best advise as to trying to diagnose your problem is to search Craigslist or Ebay for a 1986 Cadillac Deville factory service manual for purchase. That is the only way you are going to get the answer you need.

Good luck!

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Rob Painter


Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?


Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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