Question about Cars & Trucks
Hello! I have been reading a lot of posts about the BCM and what its functions are. I have a problem with my digital cluster on my 1986 Cadillac Sedan Deville 4.1. The digital dash will not opperate as it should. I do not have speedometer, mileage or trip. I do have all of the climate control functions and everything works as it should. I do not have any codes other that a persistant Coolant Fan Temp light that clicks where the BCM is behind the glove box and then does not come on. Sometimes the fans will work, sometimes they will not. Anyway..my question is about the digital dash. Sometimes all of the lights light up on the digital display and then sometimes I see a 7888 where the mileage is and nothing else. I need to know if it's the digtial cluster that is bad, or the possible BCM. If it is the BCM, can I use a salvaged part from the bone yard with just plug and go or do I need to have something reprogrammed?
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Posted on Jan 02, 2017
You have an ECM and a BCM, one located behind your glove box and the other underneath your passenger side dash. They are very similar in size, shape, and color but i think the ECM s behind the glove box. I had the same problem and replaced the one behind the glove box and the problem went away. They are both easy to replace but they cost around $70 if I remember correctly. And you have a chip you have to swap from the old to the new that you have to be careful with.
Posted on Mar 03, 2009
Flickering is not good, and indicates a deteriorating connection of some sort.
The problem is deciding if it is in external power and ground to the dash, or internal to some chip.
Clean all the connections.
Start with the battery terminals, they should be brushed shiny and then greased.
Make sure the engine ground strap and alternator connections are cleaned and greased.
Clean and check the fuses as well, with a test light, because you can't see corrosion enough to reduce current.
It would also be useful to put a voltmeter across the battery and ensure 12.5 volts at idle, and over 14 at high rpm, but not over 14.5 volts.
The next would be the connections to the back of the dash panel, which you reach from underneath. Remember the dash also have one or more ground connections.
If all that does not turn up anything, then I would suggest getting a salvage dash panel.
Posted on Oct 09, 2010
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