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1990 Sedan Deville
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4 Posts
Discussion Starter #1
Well I got in the car the other morning and anything on the dash board that has a digital display is dead. This includes my speedometer and my gas gauge! I checked the fuse and it looked good. I changed it just to be sure. But the displays are still dead. Does anyone have any ideas what may be wrong with it and have a simple fix? Thanks in advance.
 

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2001 cadillac deville base
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43 Posts
it is probably a power supply that powers the computer.

Somebody told me one time there is 2 computers and 2 power supplies...but its pretty common for the power supplies to quit after several years.

One computer provides all your display gauges and one does all the rest with the engine, tranny etc...

At least this is what I was told.
 

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1990 Sedan Deville
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36 Posts
i have that exact car, and i had the same problem, it was the BCM, i think it is located behind the glove box, we got an old one from a junk yard and it worked perfect
 

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1990 Sedan Deville
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4 Posts
Discussion Starter #7
i have that exact car, and i had the same problem, it was the BCM, i think it is located behind the glove box, we got an old one from a junk yard and it worked perfect
Was it hard to get at behind the glove box? What does the BCM look like?
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
Make sure your dimmer switch is not causing the problem.
All your displays need the 16 volts from the BCM. Behind you glove it is the biggest thing there- squarish flat silver box toward the top. On the right hand side there are two long connectors. the wire that has the 16 volts output is the orange/black wire in the longer (closer to you) connector. You can check it with a VOM for the 16 volts. It supplies the power for all your VFD (vacuum fluoresent displays) radio, Fuel, Climate control and IP. If you check it with a VOM and find that there is not 16 volts there with the IGN key ON, that is indeed your problem. Otherwise, it could be an open or short in the wiring harness problem. With power off, try reseating the connector (unplug it and plug it in again. to see if that might remedy the problem as sometimes just plain dirt/ corrosion can cause problems.
 

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'88 Eldorado
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97 Posts
Define "dead". If there's no display at all, it is not receiving power. Could be a fuse, a loose connector to the dash, or a CPS failure.

If it lights up but reads zeros and the fuel gauge flashes E, that's something else. Does it have other issues? Does the DIC say "system problem"?, Is the CC display blank? Do you have a telltale light on?

I believe a failure in multiple areas points to the BCM. It is the central processor for the car and if it develops a glitch, you can see a lot of things go wrong.
 
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