Confusing problem!

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Hi there. I am new to the boards, and really hoping someone can help. I have a 2003 LS, with about 39k miles on it.

We keep the headlights on auto setting. A few months ago, we started noticing that the interior courtesy lights don't always go on when the lights are on. The rest of the dash lights work, but the dash illumination and the courtesy lights on the console don't go on.

I took it to a local mechanic. He couldn't get the lights to work all day (no, it's NOT the dimmer switch). He said that the line had power, but he couldn't get power TO the line. Tried to replace the light switch, but that wasn't the problem. He thought it was the computer.

So I took the car to the dealer. Of course, the lights worked all the way over on the drive and all day while they had the car. So of course, they can't find a problem.

When I picked up the car, I turned on the lights - nothing! I called the tech out. He drove the car into the garage - and the lights came on. I know what you're thinking - well, you probably couldn't tell outside during the day. Nope. I CAN tell. It's hard, but there are a few spots where it's easy to see - especially right by the CD drive. There's a tiny bulb right there that lights up when the lights are on.

So the question is - is it possible that there's a light sensor that turns the interior lights on when it gets darker out? Trust me, I'm not as dumb as I sound. But I've driven this car several times when the headlights have been on (rainy day, dusk) and the interior lights are not. I start the car in the garage - the interior lights are on. I pull out, they stay on. If I have the car on during the day, with the headlights on, and the interior lights not working, I pull into the garage and after 2 or 3 seconds, they go on.

I'm just reaching out to see if anyone else has had this problem or knows of some setting that I don't. Thanks for our help.

 

[joegr]

Okay, your post is confusing. I think that you are using the wrong terms. Courtesy lights are the interior lights that light up the whole interior, like the map lights and the footwell lights. They are not supposed to come on with the headlights. They only come on when a door is opened (and for a little while after) or when you turn the dimmer switch all the way up.

I think that you are really talking about the instrument lights and the button backlights. There is only one light sensor on the LS (if you don't count the ones in the rear view mirror). If the headlights (or even just the parking lights) are on, then the instrument/button lights will be on.

The dash gauge lighting is driven by electronics in the cluster. These are also the electronics that decide when to turn the headlights on. The cluster also sends a command via the CAN bus to the FEM (Front Electronics Module) to turn on the headlights and the backlighting for a lot of the buttons, like the window switches. The cluster also sends a command via the CAN bus to the radio and the climate control to turn on their backlighting and dim their displays. (In all cases, the dim level is included in the command.)

Please indicate exactly which lights come on, and which ones don't. Don't call them something, say exactly what button or display. Also which displays do and don't dim when this happens? Is there anything else not working correctly? Is this a V6 or a V8?

 

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Thanks!! You're right, I am using the wrong terminology!

Ok. First things first, it's a V6.

And yes, I am talking about the instrument lighting and the button backlights. The gauges and console, gearshift backlights. Those are the lights that are going on sometimes, and not others.

 

[joegr]

I'm afraid that probably you are going to have to take it to a dealer while it is giving the problem so they can monitor the CAN bus and see what is happening.

 

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Thanks for your help.