Electrical prob PLEASE HELP 2000 STS

[BrianCskates]

Hi all. I have an electrical issue that's cropped up. It involves the radio(Bose w/nav), all power windows, interior lights.
When I touch the ON for the radio, it shuts itself off. The power windows, along with the switch backlighting for them, works intermittantly. At night, I can see the backlighting going on and off in no set interval. The windows only work when the backlighting for the switches on lite. The interior lights go on and off randomly when operating by the door jam switches, but work normal by setting the dome light switch to ON.

Other stuff occuring is, the speed limited to 95 or 90 (whatever it is) comes up randomly on the message center then goes away. Same with the Security light.

Code readouts are crazy. Never the same each time.

No Check Engine light ever. But whats weird is, everything works perfect with the key in ACC position, except for the interior light issue. Radio stays on,etc.
Put the key to run, and radio shuts off.

I went thru all the grounds in the car, and chopped off those "ground boxes", and SOLDERED the wires in heavy ring terminals. No change.

It seems like random stuff is just losing power intermittantly. Everything involved seems to be stuff thats fused thru the underseat fusebox. But not everything that runs thru there. I'm baffled. I've put about 20 hours into trying to fix it so far.

I'm not blowing fuses or anything, and tried a substitute battery already.
But all is well when the key is on ACC position. That's what's ruling out the obvious to me. (grounds etc).
But throwing in the interior lights issue, that's random all the time, with key in any position, really is keeping me from finding any common denominator.

I've had every cable off in the car and cleaned every terminal. It's driving me nuts. None of the exterior lights are affected, nor is the engine or tranny control systems. I've swapped around relays and everything.

Has ANYONE ever had anything of this nature happen before?

[curtc]

What are the codes that are generated?

[Mark C]

Ignition switch probably. Check your IGN3 relay in the underseat fuse block. Make sure its getting picked up when you start the car, and staying picked up. Swap the relay with some other relay as the contacts in it may be burned.

[2001_Seville_SLS]

Mark C could be right. However if your problem is intermittent it is more likely a bad connection somewhere. Check your fuses for good contact. There could be oxydation on a fuse contact.

Following is a copy of a post I made on another forum. It may be of some use to you:

"I just fixed this gremlin, so I am posting the symptoms and the solution for future use.

The car is a 2001 Seville with no trouble codes prior to the problem.

I tried to use the car three days ago and the doors were locked, but I didn't lock them because the car is parked in a garage. The doors opened with the key fob, but the car wouldn't start. It was dead. Dead, dead as in no dash, the electric windows and door locks wouldn't work, and there were no relay clicks when the key turned the ignition. It didn't start and the onboard diagnostic wouldn't work. Nothing. I got out of the car and closed the door and the doors locked behind me, only I didn't use the fob, the car locked me out. I figured that something set off the security system. So I used the key to open the door, got in and it started and worked fine for a couple of trips.

Two days ago my wife tried to use the car and it was dead, no dash, no start, no lights, no windows, no electric locks. This time it didn't lock her out. I checked the battery and the green light was glowing. I figured the battery was low so I hooked up a trickle charger. That evening, it started so we went to dinner and a movie. Three trips, no problems.

Yesterday, I tried to use the car and it was dead again. The battery was at 11.5 volts and the green light was off.

This morning, dead. I bought a new battery. (I went with the OEM A/C Delco 79-6YR, because it cost a little less than the Interstate GP79 and even less than Schuck’s Superstart. Sears had some cheap batteries, but they were both under 840 CCA.)

After the battery was installed, the security light was flashing with the key out of or in the ignition and the car would not start. I read up on the theft deterrent system. The factory manual says the theft deterrent control module commands the security indicator only when the ignition key is on so it was kind of strange that the light was flashing with the key out of the ignition.

After about fifteen minutes of flashing, the security light went off and the car went back to being dead. Just like before, only now I have a new battery. Oh well, old battery didn't have much reserve capacity anyway.

I read a bunch of prior posts on the symptoms and the rear integration module seemed to be a likely culprit. The service manual confirmed that all of the devices involved in the symptoms are controlled by the module. I cleaned ground G401, but it was not the problem. So I removed the RIM thru the trunk, opened up the black case, inspected both sides of the circuit board, and couldn't see any burned circuits. I found the rear integration module connector end views in the manual and tested the ground circuits. Both were fine. Then I tested the power circuits and found 2 volts at pin A1 the battery positive voltage. It should be 12 V. The wiring diagram showed the power came thru IGN SW 15 amp fuse.

When I tried to pull the IGN SW fuse with the ignition on, lights came on and relays were clicking everywhere as soon as I moved the fuse. This gremlin was a bad contact between the fuse and the fuse box. The rear integration module was OK.

I hope this post helps someone. "

[BrianCskates]

Thanks for all the fast responses guys. I'm going to go over all suggestions. DON'T FORGET that the interior dome lights are working sporratically, no matter if the key is off,on, or in acc. That rules out a LOT of stuff.

I took 2 vids of the code readouts. One after driving a few days, then one immediately after clearing the codes, and running them again.

Here's link to the vids:
http://www.youshare.com/BrianC/a76119/DisplaySimple

I'll post back anything new I find later tonight. Please stick with me guys, I really want to get this figured out. Brian

[BrianCskates]

UPDATE: I had the car in the shop. Turns out, the front passenger side moonroof drain tube was broken. Water has been running into the dash and behind the passenger side kickpanel for god knows how long. So the foam carpet backing was soaked. The wiring is run under the carpet instead of thru a threshold channel on there cars???? That's bright.

So wiring has been under water for who know how long. This car has been a nightmare of repairs since day one. Only owned it for like 10 months. Struts, crank sensors, motor mounts, brake problems, etc.

I traded the car in. I'm back to a Lincoln Town car, like I always had before this STS. Never another Cadillac for me.

So I guess the REAL problem is now fixed. LOL