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Cadillac Repair/1985 cadillac fleetwood display blank

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Expert: - 10/19/2010


Question
cannot figure out what controls the speedometer display its blank, just changed the main computer with a brand new one but didnt help?is it the body control module or a fuse somewhere else?

Answer
Hello,

The computer is the last thing I would have changed. You said brand new or is it from a junkyard?

You need to check all fuses! Usually, not always, when defective you see 8s.

Was it working and just quit? Or did you buy the car that way?

You are chasing ghosts here and will replace many good parts before finding out the real problem. Don't do this!!!!'

either find an electical service manual with the diagnostic flow charts or youcan try http:// www.alldata.com

if they have manuals that old pay the $25 for membership and download. That's cheaper than any manual you find. Without the diagnostic information you are working in the blind.

It could be as simple as a loose ground wire.

Get a manual and it will make this adventure simpler.

Http://www.autotheftexpert.com

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Rob Painter

Expertise

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?

Experience

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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