1989 Mondial t - interior lights do not illuminate with door open

The Owner's Manual really doesn't say much about this except for that the interior lights are supposed to illuminate when the doors open (depending if the 3-position switch is at the correct setting, of course). From what I can tell there is no relay or fuse associated with this action, but I am not sure.

I do know that some device *must* be recognizing that the doors are open so it can communicate with the interior lights and tell them to go on.

This function *did* used to work on my car until a couple years ago. I let it slide and never really was bothered by it. Now I've decided to try and tackle this.

Thoughts?

 

I have a 85 308 so don't know if this applies but until some one else chimes in:
1) be sure of the obvious...are all the bulbs good?
2) there is a delay relay under the passenger footboard that slowly dims out the light when the door closes? This function also does not work on my car. I don't know if it was disabled to preserve battery?
3) coresponding fuse/fuses okay?
4) the interior light goes on with the switch but with the doors open only the door marker lights go on. I was wondering if the interior light feature was just lost when the delay relay was disabled/broken.

Good luck hope something here was useful.

 

After you have checked the obvious mentioned above. take the switches out from the door sill and squirt contact cleaner into the switch and operate them several times. mine were corroded enough to have them working intermittantly and the contact cleaner helped.
Still not perfect but better.

 

Thanks guys.

The obvious areas have been checked -- this is purely an electrical problem.

I am wanting to know how the light gets the information from whatever source that the doors are open. From there I can try to find the problem.

 

Via the door jam switch 17 - creates a ground connection that turns the lights on because their positive side is permanently powered by the battery via fuse #4 (15A) in the left box.
Take the switch out, get rid of all the corrosion, and at the same time check the wire attached to it.
If you ground it directly, the lights must come on, both door and interior lights.

Fuse #4 powers the following:
- clock
- hazards
- 12V sockets
- daylight flasher
- interior/door lights
- radio

If these things work, the fuse is OK...
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Thanks! And how does that switch talk to the interior convenience light?

 

Just as a note. The systems from this era don't "communicate" with each other. Unlike today's digital world these are hard wired analog systems. Circuts are made and broken, things go on and off. There is no logic board or devices envolved in the door light system. Perhaps a look at the wiring diagram might detail what you are looking for as far as how the lights function the way they do.

 

The switch doesn't talk, it just closes the circuit by connecting to the ground.
As the bulb is permanently under 12V, it comes on.

As I said: battery "+" > fuse 4 > bulb > switch 17 > ground.

Somewhere, the interior lights timer keeps another ground for a little longer once the lights are on so they stay on for a minute or so after you shut the door.

 

Thank you, guys. This is helpful.

 

welcome and good luck!