Cadillac Repair: 92 Fleetwood, voltage spike, possability

Question
I have a 93 Fleetwood and when i got the car the digital dash, fuel, and A/C panels were all dark. i changed out the cluster then the BCM and ECM even the fuses. After i changed the BCM the dash and fuel would come on but would be real dim and then after a couple of seconds they would go back dark. Is there anything that i might be missing that i should check. I seen on one of your responses that you told someone to check the power supply or something in that nature. i don't know where that is but any pointers you could give me would help me out alot. i tried to get a diagnostic test but can't cause the check engine light isn't on and they told me it would be a waste of money.

Answer
Hi Gene, To help you better I would need to know if your car is FWD or RWD because both versions were called the Fleetwood except the Brougham was the rear wheel drive model.

    What I can offer at this point is since you get the dash and fuel displays to power up although dimly I would suggest unplugging the displays that still don't light up because one of them could be shorted internally and that keeps the BCM/powersource from getting any of them to full brightness. Make sure that the key is turned off when unplugging or plugging in the componants so you don't send a voltage spike and damage anything further. So unplug one that doesn't light turn the key on and see if the otheres come on normal brightness. If they do then that componant needs to be replaced. If it didn't make a differance turn the key off and unplug another one and turn the key on. There is a possability that the dash or fuel panels could be bad so try those also. Save the dash and fuel panels for last because if the dash is unplugged and the fuel is still dim then unplug the fuel and plug in the dash and see what happens.

    As soon as you find the panel that allows the others to come on full brightness or stay on start plugging in the others and see if they now light up. If they do then replace the bad one and hopefully the BCM will still be ok. The BCM is your power source on the FWD model and it needs to put out 16volts to the panel for them to operate properly. If you still can't get any panel to light then I will need to give you a voltage pin test and ground pin test to see whats happening there.

    Hope the helps. Bill