Cadillac Owners Forum banner

1 - 16 of 16 Posts

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #1
I bought my car from a used dealer...and it was a chunk when I got her. Had to replace timing chain, retime the engine, tore the heads down to clean and inspect them, purged the radiator, tranny, everything.

Car runs like a gem now, oddly enough can take down Mustangs from a dig, and I've marked a few low model Vettes. I love her to death.

The problems I am having are these:

When the car is turned off, the Oil indicator comes on, and stays on, even AFTER I yank every single fuse in the under dash panel. Also, the air glide will come on whenever it wants even if the car is turned off, I found this out because I use the trunk as a seat when I smoke. (Wife is allergic, so I smoke outside, in Texas, joy)

Now, another mechanic, with more experience than me, said it could be the PT (pressure transmitter) switch for the oil, and a locked open relay on the compressor for the air glide. Is this likely? If so, where are these two, since I am unfamiliar with the 4.9 PFI.

Also, I installed a new radio, but the idiots whom owned it before me, instead of gettting an adaptor harness, cut and connected straight to the wiring. When i put mine in, I couldn't find the power antenna cable....where is it?
 

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #3
*bumps back to the top since it's been over 24 hours and my thread went to page two*

((If I'm being annoying, just say so))
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,975 Posts
Not being annoying, but I suspect no one has an answer.
 

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #5
That's what I'm afraid of...I'd rrather not rip it apart again, since I need it to get to work currently.
 

·
Registered
Sedan de Ville, CTS
Joined
·
4,764 Posts
Take a box of donuts to the srvc mgr at local Caddy dealer. He will put you in touch with electr mechanic and give you a copy of the schematic for the radio and the suspension. If the mechanic has been around for some time, he might even have some ideas.

Good luck.
 

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #7
Alrighty, I can do that, hopefully that will help me find the suspension problem.

((And i just got me a part time job at Autozone, so I am EXTREMLY happy))
 

·
Registered
93 Sedan Deville 4.9L
Joined
·
1,005 Posts
I assume when you say air glide you mean the real leveling system?

The compressor is underneath the hood near the washer fluid. It is not unusual for it to run with the car off, now if it runs for several minutes when no weight is added or removed from the car I would assume you have a leak somewhere, Mine ran to much for my liking so I have it unplugged for now, I think it is only supposed to run 10-15 secs at once to avoid battery drain.
 

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #10
I know where the compressor is, I'm just trying to find the control relay, there should be one for it. That and the reason my oil light comes on when the car is off.
 

·
Registered
06 Escalade
Joined
·
36 Posts
If I remember right, the air ride will come on with the key off. And if your setting in the back of the truck you can put enough weight on there to activate the compressor.
 

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #12
That's just it, it will run randomly without me sitting on the car, or anything in there. I'm gonna jack up the car and look for a leak, once I can buy a new jack and some stands.
 

·
Registered
1968 Cadillac Sedan deVille, 1994 Chevrolet G20
Joined
·
2,795 Posts
Regarding the oil light, with all the fuses in, turn the key on but do not start the engine. Light still on? It should be.
 

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #14
It's not, when I turn the ignition to on, I waited twenty seconds, no oil light, it's ONLY when the key is off. WHy does this make me think it's gonna be expensive or involve taking a lot of things apart again?
 

·
Registered
1968 Cadillac Sedan deVille, 1994 Chevrolet G20
Joined
·
2,795 Posts
Ok, knowing that, you have a short to power on the switch side of the circuit.
Knowing the car has had a bit of work, it could be as simple as someone plugged the wire for the oil light into the wrong spot upon reassembly. I would start at the switch, verify its plugged in (and what is plugged into it) and follow the wire back paying careful attention to areas that would have constant 12v, even with all of the fuses out.

A possibility is GM sometimes used 3 prong oil psi switches, with a set of terminals for the fuel pump as a form of a backup to the fuel pump relay. Not sure if it is present on your car, but that would place +12v right at the switch, and if the wires weren't put back in the right spot or got pinched could easily cause the exact problem your having.

If your curious as to why the bulb is doing what it is doing, remember that the light lights when current flows through it. For current to flow, there has to be a voltage difference. In normal operation, the bulb is fed +12v on one side through some kind of ignition controlled circuit, and the other side is connected to the oil pressure switch which closes to ground when there is low pressure. When the switch is closed, current can flow, and the light lights.

In your case, for some reason, there is +12v where the switch should be applying the ground. The result is, when you turn the key on, there is +12v to both sides of the bulb, no voltage difference, no current flow and thus no light. When you turn the key off, the normally hot side of the bulb shares its fused ignition controlled circuit with a few other components, likely other gauges and warning lights. The mystery +12v source is trying to power all of that stuff through that light bulb, so current is flowing, the bulb lights up, BUT the light ends up using up enough voltage that the other stuff doesn't turn on. The other "stuff" is essentially acting as a ground.
 

·
Registered
1992 Sedan DeVille
Joined
·
35 Posts
Discussion Starter #16
Oh, goody, so I get to hunt down the PT switch, and backtrace the wires into the dash? Guess the light stays for a few more weeks.

THank you very much for the reply though, at least now I know what I'm looking for.
 
1 - 16 of 16 Posts
Top