View Full Version : Courtesy Light Circuit Weirdness/short

07-03-2006, 03:45 AM
Hi guys.
1990 S/C 5-speed.
I'm trying to restore all my S/Cs functions and I discovered I was missing a fuse, which was the courtesy light fuse/fuse for all non-ignition power sources. Basically, all the stuff will work just fine-- only when the keys are in the ignition.

So, I put in a new 10a fuse. The lights come on for a second and then POP the fuse goes. So I put in one more. Pop yet again. When I got the car, however, that fuse did not pop immediately when I put a fuse in it. It actually worked when I left it in, but I was afraid it would drain my battery. Since I've figured out otherwise since then I've found that there is a short somewhere that is occuring in the non-ignition power circuit-- you know, the standby power for your courtesy lights, keyless entry and all that crap.
All the stuff that works fine and isn't blowing fuses when you use it-- overhead lights, doors etc all works, except when the key isn't in the ignition.

The other thing is, when I bought the car, it had a functional cd player. The CD player will no longer power on when hooked up in the car. So far as I can tell everything is there, but I just can't seem to find what the hell is shorting because every wire I find that isn't connected to anything is promptly capped and wrapped in electrical tape if I don't know what it goes to. How would I test and hunt down whatever's causing the lack of juice to the player.
It's not a fuse since all fuses and fusible links are just fine outside of the courtesy light fuse, and the VMM above it still comes on just fine, and my ac controls all work -- only the radio is out. I yanked the thing out and went through its harness and found two loose wires that needed to be taped up, but after that everything appeared to be intact if not a little messy.

Any ideas on where to check, what could be causing the short etc etc.
Any input is much appreciated!

Thanks very much,
Los Alamitos, CA

Where would I look for a short, and how would I test for it?

07-03-2006, 09:11 AM
Sounds like you might have a bad ignition switch......

07-03-2006, 03:03 PM
The ignition switch would short the courtesy light circuit?

07-03-2006, 04:38 PM
Everything works fine until you put the key in and turn the ignition switch on?

07-03-2006, 04:42 PM
Just another thought......

Check the wire bundle under the drivers side carpet.....

Look for the green/yellow wires that go to a splice (it will be three wires going into four wires).....

There might be something there that could be causing your problem....

07-03-2006, 07:21 PM
no no, everything works AFTER you put in the key and turn it on.

07-04-2006, 01:40 PM
Could still be the ignition switch. When it separates, one side or the other will break free first. So the problem could either occur when turning on or be fixed by turning on. 3 screws will remove the shroud and you will know immediately if that was the problem. Disconnect the battery before messing with it to much.

07-04-2006, 06:18 PM
How can I tell?

Presently the ignition lock cylinder appears to be ~~~~ed up, as it no longer accepts my key into the socket but will turn on/off anyways.

How much do ignition switches typically run?
I should probably buy it asap since my discount at autozone goes up to 30% for july 7,8,9.

Additionally, could the failure of this circuit be causing my radio not to turn on?

thanks much,

07-04-2006, 06:35 PM
He's not talking about the locking key cylinder. He's talking about the ignition switch located under the bottom right of the steering column. They get old and come apart thus breaking the circuits.

Remove the steering column trim and you will see the switch and you should be able to tell if it has seperated or not. Mine did on the 91 I had and I fixed it with zip ties. :eek: ;)

07-04-2006, 11:35 PM
I bet that's what it is. I'll give that a shot.
It's just 3 bolts to undo the steering column shroud, right?
~~~ does the switch look like anyways?


07-05-2006, 07:39 AM
Once you have the shroud removed, (sitting in drivers seat) on the right hand side. You will see the key cylinder and a metal rod going towards the front of the car that is connected to about a 2 - 3 inch switch connector with LOTS of connections. That be it. Disconnect your battery before hand because the metal rod from the locking cylinder hooks to a slider in the middle of the 2-3 inch switch. If it is separated, it has the potential of touching all the WRONG STUFF.

If it is the switch, RadiumSC's fix takes about 3 mins (and a few donor wire ties).
Good Luck

07-05-2006, 09:31 PM
Well, the ignition switch is all fine and dandy, apparently.

After playing with it a bunch, the car now accepts fuses and the courtesy circuit is back.
However, I am not sure if this is normal:
The red battery indicator is on
The VMM remains on constantly
the firm ride light will start to blink after a while when the car is off.
The fan must manually be turned off.

Since I don't really think that the VMM, battery indicator and firm ride light consume a whole lot of energy, I've elected to leave the fuse in.


07-06-2006, 02:29 PM
It still sounds like you could have a problem with the switch to me. If those things you mentioned weren't doing that before you played with the switch and they are now, I would think that switch could be faulty or at least some wiring going into it or coming out.

07-06-2006, 02:44 PM
I suppose I should probably just give in and buy the damn switch.
The other thing is my aftermarket stereo that USED TO WORK a few days ago doesn't anymore. The fuse on the back of it is still good but the bastard won't power on. I hate it anyways, and am going to be installing a ford cassette deck out of my girlfriend's 00 mustang to replace it. It still has some of the connectors and that weird L-shaped dealie with the gray wire plugs into it, now I just need the ford 6-pin hookup. I am going to try to get that installed tomorrow.

The bird's coming along pretty nicely, thus far I haven't had to spend hardly anything to restore its functions. Oh, and after running seafoam I'm up to 12psi of boost at WOT. hehe.

Anyways, that's about all.