2000 Malibu LS, V-6. I got the car used, so I'm not intimately familiar with its history.

Whenever the car is on, the exterior lights come on. Not the DRL's, but the headlights, sidemarker lamps, tag lights, tail-lights, parking lights, all of the lights that would normally come on when one turns on the headlights. I know the headlights are supposed to come on automatically, when its dark, but they come on during the day, when other Malibus on the road don't have headlights on.

I tried applying the parking brake to disable the lights, just to test that part of the system, and that worked properly. Parking brake on, no exterior lights come on.

What should I look at as a probable cause?

I'm guessing it could be the sensor, that is supposed to be in the vent under the windshield. But I haven't found anything that shows me exactly what that looks like. Is it the small spherical looking thing, poking up, towards the driver's side, or is it buried down one of the holes visible through the vent? I really don't want to tear the dash apart to replace that, but...

Or maybe the headlight switch itself, which seems to be somewhat costly, as its a multifunction switch?

I'm going to go play around with the relays and fuses, just cause they're accessible and cheap, but does anybody have any ideas? My grasp of electrical matters is pretty limited. Any ideas?

 

I believe it is that "spherical looking thing poking up" which is the photo sensor.

Try cleaning it , there may be something coating it ( like Armour all ) not allowing the light to penetrate the cover.

Although I haven't heard of this system malfunctioning it's possible that the photo sensor could be faulty or may be the lighting module.

btw... is there an aftermarket remote starter wired in ?

Other than being an annoyance to you , it's not a bad thing to drive with your lights on.

 

Follow up to my original post:

I checked further. When my parking brake is applied, the lights do not come on, but as soon as the brake comes off, they come on, even in park. I was thinking it might have something to do with the DRL sysytem, but they're not supposed to come on until the vehicle is not in park, so the DRL system may not be the problem. The lights can be turned on manually when the parking brake is on. The sensor might be the problem, so I'll try cleaning it. I know I applied "Armor All" after I got the car, but I'm fairly certain the problem was there before I got the car, and it sure didn't feel like the dash had ever encountered "Armor All" before then.

The car doesn't have any aftermarket electrical stuff added to it. The car belonged to my mother. It had been in an accident before I acquired it, and I'm discovering that the repair might have left something to be desired. The A/C wasn't working properly when I got the car. Repair shop discovered that there wasn't an orifice tube installed. That part of the A/C system was probably damaged in the accident, and was probably "repaired" as a result of the accident. They might not have done something else right too.

 

Tried cleaning the sensor with a cotton swab soaked in a cleaner. Still, the lights come on...

 

Follow-Up:

Thank you "Golfer". I started focusing in on the sensor after your post. Even though I cleaned it, I was still experiencing problems. I was hesistant to use anything too strong to clean it, because it appears to be plastic. After a while, I figured I was going to have to replace it. I decided, what the hell, and cleaned it with a cottton swab soaked in mineral spirits. A few days lapsed before I drove the car again, but I drove it yesterday, and the lights are working like they're supposed to. Just the DRL's came on. Pulled into my garage and sat for a bit, and the headlights came on. Pulled out of the garage, sat a bit, and the headlights went off, DRL's came on.

And even though having the headlights on all the time isn't bad, I feel better that its working like it is supposed to.

 

mine does the same is normal for a malibu