Instrument panel and A/C controls are not working

CRAIG_CLAUDIA

MEMBER
2003 CADILLAC STS
4.6L
V8
2WD
AUTOMATIC
180,000 MILES

Everything else seems okay. New battery and alternator so far. Also, the door chimes ring even without the key in or lights on. I believe it is one of the body control modules, or the ignition switch. I can't afford a Tech 2 scan at the dealer, not sure that would help. How best to diagnose? I do have the huge service manuals.

Friday, October 29th, 2021 AT 3:58 PM

4 Replies

ASEMASTER6371

MECHANIC
52,796 POSTS

Good morning,

I attached the wiring diagram for the instrument cluster for you.

https://www.2carpros.com/articles/how-to-check-wiring

You need to test the 2 fuses I highlighted for power on both sides when the key is in the on position. 1 fuse is in the under-hood fuse block and the other is in the rear fuse block.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know the results so we can proceed. Hopefully, it is just a failed fuse for you.

Roy

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Saturday, October 30th, 2021 AT 4:01 AM

CRAIG_CLAUDIA

MEMBER
3 POSTS

Roy,

Thanks for replying and your interest in my problem. I will test for power on both sides (with key on) of what looks like fuse #7 front, and #12 rear.
In the meantime, I finished the alternator replacement which fixed 2 issues, no more parasitic drain on the battery, output current a fairly steady 14.6 volts.
The old alternator showed 15.85 volts. Probably 1 bad diode in the rectifier?
I will check and report on the fuses sometime tomorrow. Thanks again!
Craig

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Saturday, October 30th, 2021 AT 10:19 PM

CRAIG_CLAUDIA