Automatic Headlight Question

ScottyBoy · May 26, 2009

I have a 2001 Suburban with the automatic headlights. They automatically come on at dusk, or if I start the truck and its already dark outside. Lately, they seem to have been acting up. The headlights will come on during the day. At first I thought it may have just been because it was a very muggy/cloudy day, but then it did it a few times in very bright pure sunlight.Some days it will do it, other days they will stay off. What could be happening here? Could the light sensor on top the dash be going bad? I usually wont even notice they are on until I pull up behind a dark colored vehicle at a stoplight and see my headlights reflecting off the dark paint. Or sometimes driving in a parking lot towards a store window, I'll see the reflection. In the past week or so, I only know of two days that they didn't come on during the day, just the drl's were on. Has anyone ever heard of this issue happening? I'm wondering if the light sensor is bad, or then again, if it was bad, would the lights not come on at all, even at night?

bossier62guy · May 26, 2009

I have a 2001 Suburban with the automatic headlights. They automatically come on at dusk, or if I start the truck and its already dark outside. Lately, they seem to have been acting up. The headlights will come on during the day. At first I thought it may have just been because it was a very muggy/cloudy day, but then it did it a few times in very bright pure sunlight.Some days it will do it, other days they will stay off. What could be happening here? Could the light sensor on top the dash be going bad? I usually wont even notice they are on until I pull up behind a dark colored vehicle at a stoplight and see my headlights reflecting off the dark paint. Or sometimes driving in a parking lot towards a store window, I'll see the reflection. In the past week or so, I only know of two days that they didn't come on during the day, just the drl's were on. Has anyone ever heard of this issue happening? I'm wondering if the light sensor is bad, or then again, if it was bad, would the lights not come on at all, even at night?

I'd go for the sensor....

bill190 · May 26, 2009

Is there any dust or dirt on the sensor blocking light for getting to it?

ScottyBoy · May 27, 2009

No, it seems to be clear. I tried shining a flashlight (big 3D-cell maglite) directly into the sensor thru the windshield and the lights will still stay on. Is there any way to test this light sensor? Should it be a certain resistance on a multimeter or something?

bill190 · May 27, 2009

A GM factory electrical diagram manual should have procedures for testing it as well as troubleshooting the problem.

ColoradoSkiCountry · May 28, 2009

Make sure you have that light on the sensor for a good full minute. The sensors are not "instant On/off" type.

Frost · May 28, 2009

Any resolution on your problem? I'm having the same issue on my 03.

ScottyBoy · June 2, 2009

Still not working right. And yeah, I had the light over the sensor for at least a minute or so. Anyone have a factory maual with the electrical diagram for this?

bossier62guy · June 2, 2009

Still not working right. And yeah, I had the light over the sensor for at least a minute or so. Anyone have a factory maual with the electrical diagram for this?

So obviously the sensor isn't working properly....i think i'd just replace it or put a resistor in it's place and use the headlights manually....

y2kz71 · June 2, 2009

Still not working right. And yeah, I had the light over the sensor for at least a minute or so. Anyone have a factory maual with the electrical diagram for this?

So obviously the sensor isn't working properly....i think i'd just replace it or put a resistor in it's place and use the headlights manually....

I agree...disable that thing

Are your HID's wired up with a relay?

I have seen the cheap chinese relays go bad and cause a similar malfunction

ScottyBoy · June 2, 2009

Still not working right. And yeah, I had the light over the sensor for at least a minute or so. Anyone have a factory maual with the electrical diagram for this?

So obviously the sensor isn't working properly....i think i'd just replace it or put a resistor in it's place and use the headlights manually....

I agree...disable that thing

Are your HID's wired up with a relay?

I have seen the cheap chinese relays go bad and cause a similar malfunction

No, they don't have a relay on them. It's nothing to do with the HID's, because the switch will still control the lights every other way. I can manually turn the lights on or off with the switch(if the ign is off). I can disable the the auto headlights by pressing the dome over ride button (which is what I pretty much do every time I drive during the day now) but it also shuts off the DRL's as well. I'd like to get everything back working the way it should.

y2kz71 · June 2, 2009

if its not the sensor then its the body control module

jrrod2004 · June 2, 2009

Still not working right. And yeah, I had the light over the sensor for at least a minute or so. Anyone have a factory maual with the electrical diagram for this?

So obviously the sensor isn't working properly....i think i'd just replace it or put a resistor in it's place and use the headlights manually....

I agree...disable that thing

Are your HID's wired up with a relay?

I have seen the cheap chinese relays go bad and cause a similar malfunction

No, they don't have a relay on them. It's nothing to do with the HID's, because the switch will still control the lights every other way. I can manually turn the lights on or off with the switch(if the ign is off). I can disable the the auto headlights by pressing the dome over ride button (which is what I pretty much do every time I drive during the day now) but it also shuts off the DRL's as well. I'd like to get everything back working the way it should.

replace the ambient light sensor