Dome Light - Only Comes on in the 'Always On' position.

Since I got the 355 6 weeks ago, the Dome Light has not worked properly. I've done a search of the archives and found a few 'Dome Lights Stuck On' threads, but this unfortunately is not my problem. Mine won't come on - at least not via the door switch(s).

Here is the scenario:
1. When sitting in the 'neutral middle position' it does not light when doors are opened or not - I think this is the correct result
2. When pushed in on the windshield side, I get the same results - it does not light with the doors open or closed. This should be the 'automatic mode' which lights the light with the doors open.
3. When pushed in from the 'rear' side, it comes on and stays on - which I think is the correct behavior.
4. The console button 'aft of the hazard light' has absolutely no impact on any of the above three outcomes.
5. The red lights in the doors do indeed light when the door is open, and the switches for the windows illuminate as well.

So, I've taken the dome light out and here's what it seems like we've got:
1. Looks like maybe the hot (+ voltage) is wired right into one side of the circuit (i.e. not switched) and directly contacts the bulb.
2. Looks like on the other side of the bulb, having the light in the middle position puts the ground connector for the bulb against an insulator (hence no circuit)
3. With the light in the 'pushed in rear position' the ground connector for the bulb is against the metal frame of the light itself (which has a ground connector as part of the frame). This makes sense as it always completes teh circuit and lights the light.
4. With the light in the 'pushed in windshield side position' it looks like it puts the ground connector for the bulb against a contact wired in from outside (guessing this would be a ground coming from the door switch). This seems to be what is failing.

Now, if I could only get my damn Fluke multi-meter to work, I'd be able to check out the wires!

Any insight, correction to, comment about, or general sympathy regarding the dome light or my conclusions above is welcome!

 

Well, I can see that dome lights aren't a popular topic, but I've never been one to be discouraged easily!

Just for the record, when I managed to get my multi-meter working, it seems that what I assumed was a ground circuit appears to be +12v. I still can't 'accept that' since it's the frame around the light - of course it was 3am when I took the measurement, so perhaps I was seeing things. When I return home, I'll check it again.

Is there a circuit diagram for this light switch somewhere?

 

Hate to show ignorance, but are you talking about a delay which turns the light back off after the door is closed again ... that kind of delay?

Unfortunately, I have already done the 'hard reset', but there was no impact on the lighting circuit. Must not be a Microsoft product.

 

Admittedly, I haven't explored much around the door switches, only because I was playing the odds game that since neither door triggered the switch, that odds were better the problem lies elsewhere.

It would be really helpful to have a circuit diagram, as it strikes me as bizarre that I'm measuring 12v on the connector that connects to the light frame itself. It's either that, or it's a ground and I've got -12v running around my car as well!

Yes, the alarm works the same now as it did when I got the car 6 weeks ago. Of course, I guess that's not saying much since the light didn't work then either!

 

Sorry for delayed response... work, travel, etc.

Wow, lots of good information in this post and all the ones that followed. Many of the above questions I can't answer until I get a chance to open up the car tomorrow. However, the fact that I didn't even know there WAS an ignition light says mine probably doesn't work. But where the heck is it located? I took the entire steering console apart when I 'fixed' the sticky problem and don't remember seeing a light anywhere near the ignition.

With respect to measuring the voltage, I wasn't actually measuring through the light (and bulb) because I had actually removed the entire light and was measuring the actual wires to the light. The wire that attached to the light frame (not saying it was wired correctly when I bought the car) measured 12v with red wire on this connector and the black on either of the other two wires. However with the information above, I'll take it apart again and insure the connections on the light align with the wiring guidelines specified above ... thanks SO MUCH for this information. What you described is EXACTLY what I expected to find after examining how the light worked once it was apart and I could examine what circuits were completed in the various positions.

One of the reasons I can't go check some of this now is that I blew a fuse when I put the light back in last time and did a bit too much experimenting. I had to go buy fuses (which I needed to get anyway).

I'll let you know what I find out...

 

So, as I mentioned in my earlier post, being an electrical engineer, the fact that the frame of the light was wired to 12v really bothered me. I was suspicious that my wire should NOT have had 12v on it. Then in David's reply above, he gave me enough information to verify I had the right voltages on the right wires. HOWEVER, that doesn't mean the wires are going where they are supposed to be going!!! (insert light bulb here)

Sure enough, as I looked at the light coupled with wire information David provided above, it was indeed mis-wired. The ground wire SHOULD have been going to the frame. So the next question is why would someone re-wire the light? Well after re-wiring using the logic of how things are supposed to work, I figured out why someone played with the wiring. When properly wired, the 'Auto' position leaves the light always on... this is not surprising as the black & white wire is always ground. I read 12v between it and the orange wire with doors open or closed (even several minutes after the door is closed).

So, do you think my 'time delay' circuit is to blame for sending ground through the black & white wire all the time? Either that or the passenger door switch is not working and always shorted to ground (since it bypasses the time delay circuit). Interesting dilemma.

BTW, still don't know where this 'ignition light' is supposed to be that folks are talking about in the posts above. I obviously do NOT have one that works. What lights up?

 

Sorry, I've been away on vacation skiing in Colorado.

When I said the black/white wire was always ground, it's not because I'm connecting it to ground, I'm just always seeing it as a grounded wire. It's always reading as grounded even though as you indicate it should be switched, so the problem is likely on the switch side or the timer circuit. Perhaps I should see if I can get a replacement part for the delay timer. The door switch on both sides seems to work the red door lights just as expected... not sure if they use the same wire or not, but if so, it seems the switch is working.