Cadillac: 1988 Cadillac Coupe DeVille, cadillac coupe deville, digital speedometer

Question
QUESTION: I just put in a new battery and alternator for my '88 Cadillac and everything was working fine until I noticed my digital gauges went blank....all the panels light like but nothing works...I can't see the digital speedometer or fuel..even my heater and AC wont come on now...what could be the problem?

ANSWER: In any of the displays is there a:

-c
-d
-151

being displayed or are they ALL completly blank ?.

If the AC/Heater blower motor is running push the OFF button.  Is the blower now OFF ?.

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QUESTION: I did not see any of display shown on my gauges. I can't see what fuel gauge is reading nor I can't see the speedomter. The AC/Heater will not come on either. The lighting elements do work however when I turn on the headlights. I checked all the fuses and they're not blown. Is there something I'm not checking?
ANSWER: The most likely cause is a faulty BODY CONTROL MODULE (BCM) that will need to be replaced.

I have heard from a couple of people of a procedure that they did and it corrected this problem. Now, I have NOT tried this procedure and do NOT know if it is a valid procedure or not but if you want to try it here it is.

Disconnect the battery and turn ON the headlights for 2 minutes and then turn OFF the headlights and then reconnect the battery and see if your fault is fixed.

PLEASE let me know if thios works or NOT.

---------- FOLLOW-UP ----------

QUESTION: Well my next step is to check the BCM module. I tried the procedure you provided me (disconnecting th battery for 2 minutes and turning on the headlights). However that did not work. Someone told me that I also might have to replace the instrument cluster? Could this be true? And also how do I check the BCM if its faulty or not?
ANSWER: Turn ignition ON, Engine OFF.

Push FRONT DEFOG button. Does blower operate ?.

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QUESTION: I tried doing that also....and it doesn't want to come on.

Answer
Depending upon your mechanical ability to use a test light and a digital volt meter to perform some simple test procedures on the displays and the computer, I can provide you with PICTURES and instructions on how and what to test to find out if your fault is the BCM and or the instrument cluster. E-mail me at: onlineautohelp@msn.com