This is what I keep reading.. https://www.gmforum.com/attachments/...osis-chart.png

It says if lights do not work ONLY when the switch is stuck in the ON position.
I wonder if a bad switch could cause the switch to be stuck in the ON position?
Then again they'd probably have worked without cutting off for a while, and that has never been the case.
Still in the morn I am going to jump test them switch, and if I get no lights I may not waste my money on the switch.
It is supposed to rain now, so I doubt I'll get the seats out.

I wonder if it would do any good to check one of the interior lights, maybe see if there is a lack of ground, or if is a lack of power?

Do you have room at your place for one of those carports that sell for about $600 ?
Just a thought might help keep you out of the weather so working on your car is at lease dry.

I looked over a few, but all the cheap priced ports said they don't hold up well in the wind, plus I am not sure if my landlord would allow me to out one up, he is picky about the way things look around here.
There are so many trees, they are all around my two spare parking spots, I could probably park in-between them, and tie my tarp to the trees above my car, but if I left it up for long he'd probably complain.

On your year vehicle, I think it is under the Passenger seat....if there and the carpet under there is wet, it could be starting to corrode....if your air bag light counts to 7 and goes out, it is still ok.....but it'* just a matter of time before corrosion, in the form of green connections, rears it'* ugly head....

Customers never liked it when I told them, their seats and their entire carpet had to come out(sometimes the jute padding had to be replaced, because it stunk so bad).......with everything out, then the car had to be soaked to find where the leak was coming from(more often than not, the water barrier in the doors)....all grounds had to be cleaned/repaired.....and if an SDM was located on the floor, it had to be disabled, and the harness disconnected, to check for corrosion....sometimes, only a harness pigtail, needed to be replaced.......it usually took days for the carpet to dry out.... one heck of a bill.....

Yeah you are right, found it mentioned in the FSM, it is under the passenger side seat.
I have never paid attention to my airbag light, I am not sure if it flashes when I first key on or not, I'll check here in a few.
With how long the water has been coming in, it would be a miracle if corrosion has not already started.

I am sure jute padding will have to come out, half of it in the back was so wet it fell apart when I grabbed it, and I can only imagine the mold/mildew it has on it.
It does not smell appealing, that is for sure.

I plan to remove the seats, take the carpet out, and try to scrub it with some soap or something, and let it dry for however long it takes, I am just not sure where I'll be able to let it dry, rainy season is coming here.
I was thinking of using baby powder all over the areas where I suspect water coming in, and for areas where that is not possible like the lower windshield, I was thinking soapy water and an air compressor.
If I find the leaks for sure I'll proceed to clean up the seats, replace the nuts/washers that go on the seat bolts, as they have a tad bit of rust.
Then I may replace that jute padding, but if it is too costly I'll just put the carpet back, and deal with a little road noise.
Or does that padding serve any other purposes?
I'll read the FSM and see how to disable SIR, then examine the SDM, if it is cleanable I'll clean it, if not I'll look to replace it.
I'll track down any grounds, inspect and clean them up, put some dielectric grease on them, and tape them back up..

As for my twilight sentinel switch, I removed it and fuse jumpered the dark blue to black wire, and nothing happened, so that switch must still be good, at least I think it is.
My headlight switch is making a concerning buzz again though, and now it does not matter if the twilight sentinel has the headlights on or off, as soon as I press either switch on my door panel headlamp switch, I get an immediate buzzing sound, not sure if it is coming from the doors tweeter or what, but is is easy to hear..

Here is a video with the sound of the buzzing.
I am not sure, but maybe that is coming from what used to be the door chime thingy, I have not really heard it chime that it is supposed to for a long time, then again I bet that is because I never got the extra stuff for my aftermarket stereo head unit to retain that feature.
It still sounds like maybe it is coming from there, maybe it is from a failing multi-function switch, or ignition switch that could be making it think the key is always in the ignition, then again you'd think it would buzz any time while the door was open, and this buzzes with the key not in the ignition, and it does not matter if the door is open or not.
The buzz kind of sounds like it is coming from under the dash, a little towards the centr of the car maybe.

I checked and I never see an air bag light come on, so I am not sure if the bulb is burnt out or what.
I did look at the diagnostic info on troubleshooting that, and wow there is a lot you have to do to find out just what is causing the problem.
If the SDM got soaked and corroded, and the system, could not start the check, then you'd think the light would come on and stay on, or set some sort of DTC..

Ok I figured out that noise, it is normal, and it stops when I turn the key to the ON position.
But, I am not sure if this is normal, the twilight sentinel switch cannot be turned off, which is all the way to the left, if it is all the way left, and I cut the lights on via door panel light switch, then the lights won't come on.
If I have the twilight sentinel switch turned on, which means slid a little to the right, or all the way, then I can turn the lights on and they will come on, and stay on as they should, even if I cut the head/park lamp switches off, that is they stay on till the twilight sentinel timer turns them off, after I exit the car and take the key out..
I thought no matter what if I turned the headlamp manual switch on, that the lights would come on, I did not know the twilight sentinel switch had to be on.

I tried to remove the seats, but I found that the rear right passenger side seat already had one nut missing somehow, how I have no clue.
I tried to remove the other nut beside it and it was rusted so bad it would not budge, so I am letting it soak in penetrating spray over night.
The more and more I look at how this water has caused issues, I am starting to think it is time to just sell it as is to somebody for either parts, or as a fixer upper for a kids first time car.
If somebody removed the seats, fixed the water leaks, cleaned up the floorboard and all grounds, then possibly replaced the SDM or the pigtails to it, then washed the carpet and put it back, then they'd have a decent 1st car.
The motors compression was tested and good, maybe a little carbon buildup on cyl 6, and a tiny tiny bit on cyl 3, all other 4 cylinders are almost exact on compression numbers from 145 to 150.
I replaced the fuel pump in 2012, also the MAF, and CKP, I did the UIM/LIM job, also replaced the oil pressure switch, and the coolant temp sensor. I put in a new thermostat, and I ported the LIM to 1.9 x 0.9 like it should have been via the factory sand casting, did not polish it though, because I did not match it totally to the heads, just to factory casting specs, I did however knock off some of the rough of the LIM runners..
While I was doing the UIM/LIM I cleaned the throttle body well, even the butterfly valve..
Transmission is holding up, and should get a few thousand more miles out of it, if not dogged out, I changed the filter and fluid like 2k ago, used Mobil 1 Synthetic as I have always used.
I replaced both headlight assemblies about a year or so ago.
About 3-4k ago I replaced the rear air struts, the front are due to be replaced, but due to mileage, not wear on them, they still feel good to be original..
The water-pump is only like 3 years old, and I went with the best one.
Tires are almost new, only have like 1,000 miles on them, paid like 315.00 total for them.
I have a space ICM, PCM (already programmed to the cars VIN), and I think I have a spare TPS somewhere.
I have brand new brake drums and shoes, also rear wheel cylinders in a box, also have Castrol Synthetic brake fluid for a full fluid replace when the rear brakes need servicing, they are fine atm though.
I even have the over sized oil filter, and 5 quarts of oil for the next oil change.
Trying to think of what else I have, I have some brand new tire chains, but if they fit the new car I get, then I'll keep them..
All in all I think I have a few hundred dollars in parts, so even if bought for a parts car I think somebody should give me a few hundred for it, I'd really like to get 1,000.00, as if somebody put a little time into it they get have a decent first car for their child, the car is a very safe car to drive, as long as the rust has not gotten any worse than what I have seen.
Suspension seems fine.
If I get this Grand Prix GT then sadly my ole PA is going to be sold, or sent to a parts yard, I need to get a job ASAP, and won't have enough time to do the things it is going to need me to do to get it back to being the car I loved to drive.

Ya your painful situation sure reminds me of my olds, that I poured mega $ into.
Trunk water leaks from wheel wells repaired, leaky windshield, rust repaired twice, & still leaked!
Kept blowing interior light fuses, shorts from leaks under dash on & on.
Drove it to the scrappers, even tho I really wanted to drive it into back woods and use it for target practice!
I think at some point a car reaches a headache zone, and I was way past that with olds.
Years later after buying a new 4x4 and obtaining the PA, I really don't miss the Olds at all, even tho it was my favorite car for many years.
You are best to find a newer reliable ride now, and either keep the ole PA to work on, or try to sell it "as is"
Just make sure whatever you buy is not someone else'* higher mileage headache!
Get a good inspection done before you buy!