vilhelm

I know its here someplace...let me have another look.
any one watch "The big Labowski"?
I've read a thread on this subject but couldn't find it in my brief scan..so here goes:

1. the interior light is a 3 position switch...on; off; door activated.
2. the door switches are grounding switches...ie. when the door is closed there is not contact to ground made by the switch. So when a door is open the switch makes ground and the light comes on. when a door is closed..circuit broken..no light.

3. my interior light is on all the time unless I put it in the off position.
4. there are two ground connections to the switch...one goes straight to the chassis and the other goes to the door switches. so..when you are in the "on" position contact is made straight to the chassis and the light is on. when you are in the door activated position the light won/t come on until a door is open which allows the door contact to make ground completing the circut and the light lights.

5. My way of thinking says that there should be no conductivity between the door switch ground wire and the chassis ground wire coming from the interior light switch. (very high resistance). However...I have 1.9 ohms. This says to me the door switch ground wire is shorted (kind of) to chassis somewhere.

6. however the car still knows when the doors are open or closed because I still get the warning beeps when the door is open so 1.9 ohms isn't bad enough to mess that up or else we would think the door was open all the time.

any ideas here...? and I don't see any obvious way of replacing the wire from the interior light to the door switch..is there?


sorry for rambling...its late

GeoC2cab

High,
I dont know if this will help but it is just a suggestion, the interior light has a 20 second delay(it should go out at 20 sec. after the door is opened or shut)when set in the door position, set it there and see if it goes out after 20 seconds, only thing I can think of(it fooled me once).

Adrian

Dear Vilhelm,
The most common cause of this problem is a contaminated (water) switch. They are so crude it is not funny. They are a plastic plunger with a terminal pushed onto the end which makes contact with the mounting when open and the plunger moves the terminal away when the they are pushed in.
Sometimes you can clear the contamination by just pushing the switch in and out quickly yourself. They are fairly easy to access through the side trim.
A very common problem is that the wire falls off the terminal and sits on metal.
I am sure if you access the switches you will see the problem. Running a new wire is not that difficult actually. Getting it to run through all the roof trim is probably the hardest bit,
Ciao,
Adrian
911C4

PS: A comment was made about the light remaining on for 20 seconds. Depends which model you have. I will check when I have time to see which model this was introduced into. I know the 1989 K series C4s here in Switzerland do not have this function.

Steve Nugent

Couple months ago, my interior lights were staying on as well - spent a ton of time trying to think thru the issues - until I stopped by my mechanic one day and they fixed it in 15 seconds> Seems there's an easily bent piece of metal on the top right side of the trunk compartment which pushes in the little black plastic plunger-thingie which activates the trunk light - if it gets bent downward about a 1/4" or so, it doesn't push the plunger in when you close the hood and the interior lights are wired to stay on. If you're like me, you turn off the interior switches and decide to worry about it some other time - until the trunk light runs down your battery and the car won't start. If your trunk light goes out when you close the hood, bend the metal piece up slightly and VIOLA! At least this solved my problem and has proved to be the cheapest repair in the history of my '91 C2. Good luck - Steve

Steve Nugent

Sorry - should have said - "If your trunk light doesn't go out when you close the hood..."

Steve

vilhelm

I don't know if I'm supposed to have a 20 sec delay...but when I was working on this I let the lights stay on after closing the car door (in both positions) long enough to go into the house and grab a beer.

The switches are quite simple...while I was working on this I had both door switches pulled out and hanging isolated from all metal. That should take the switches totally out of the picture..but the lights stay on.

one thing I don't know is if the trunck light stays on when it is closed..so I'll check..kind of like checking to make sure the light in the refigerator really goes out when you close the door.

sullivs

Bruce,

Check the switch in the trunk, as the other responses mentioned. I had a similar problem with the trunk switch.
Steve

Adrian

The trunk switch has no impact on the interior lights. The trunk switch activates the trunk light and supplies an input to the alarm. The trunk and engine switches are checked when you have flat batteries and no other indications.
The interior lights are obviously earthed out somewhere. Please remember that each door switch also supplies a signal to the alarm. In its current situation the alarm system will be activated but will not work.
Check for wires snagged onscrews. Has anything been installed recently which had you working behind the dash or around the door pillars.
I would also remove the light assemblies and check them. Maybe the earth is connected via a failed light mechanism,
Ciao,
Adrian
911C4

DaveK

Hi,
The trunk switch definitely does affect my interior lights - in fact they all seem tied in together. If I open the engine cover, the interior lights come on. If I open the trunk, the interior lights come on. If I open the doors, then as well as the interior lights I can also see the engine cover light comes on (through the spoiler vents). Maybe model specific?

Dave
90 C4

vilhelm

I checked the engine cover..the light goes our and on as it should. I don't have a light in my trunk area. Should there be one?

Adrian..you said interior lights as in more than one. I have a cab with one light centered over the windshield...is there more than that?
as far as the alarm goes...yes it is activated but the doors know when they are open or closed because the warning chime sounds appropriately. Is there a way to check if the alarm is indeed working?

I guess the easiest way to check if I have a wire grounding is to disconnect the existing wire to the door switch and run a new wire from the light to ground. Then I can make and break the ground connection as if the door was opening and closing...if the existing wire is the problem the light should work as expectec with the new wire. Then I can figure out how to run it if I need to.

cheers

Adrian

Dave
Sounds like some rewiring has been going on here. If this is model specific it is not shown in the wiring diagrams. This also could be a national requirement. A change to the warning chime was made in the 1991 model year.
Vilhelm
Coupes have two lights. Cabs only have one. Targas also only have one.
The warning chime is activated by the GONG relay. This is a separate unit installed into the 964.
The trunk should have a light. It is right up by the left hand hinge. The switch is mounted in the hinge.
Checking the alarm is actually not easy.
The alarm is ONLY activated when the doors are shut and locked. So what I do to check is to pop the trunk but do not release it from the catch. Shut and lock the doors and then release the catch and open the trunk. This should set the alarm off if the switch is correctly adjusted. There is no other way to check the alarm unless you try and force the door without opening it. I did get the alarm to go off with the central locking unit removed some time ago. Again of course the alarm system may not be factory or maybe be enhanced. However it is another subject.
You are getting an earth to the interior light and you need to find where this is coming from,
Ciao,
Adrian.
911C4


One interesting thing with the Cabs. They also have an alarm switch under the rear cover. Parcel shelf. There is another switch in the glove box.

Randall G.

Second Dave on this one. Last weekend, I was working on the car with the trunk open, doors closed. Da' wife started to nag me that I was going to wind up with a dead battery because I was going to forget to turn off the interior light. I informed her (gently) that I hadn't turned the interior light on--that it would go out when I closed the trunk.

I also know of another way to check your alarm's operation. Power down your driver's side window, lock the doors with your key and wait for the alarm to set (speed of flashing LED in door-lock slows). Then, reach inside the car and try to unlock the door with the interior rotary ****. The door should re-lock itself, and the alarm will sound. This approach has worked on my car since I brought it home from the dealer in '92.

slant911

I know this maybe starting to get off the light topic, but, after you set off your alarm as described above how do you turn it off?

Randall G.

You need to use the key to unlock the door, which turns off the alarm.

slant911

Randall,

You are always full of good answers. Thanks.

John