I think something is wrong with my automatic headlights. I noticed the last few days at dusk(when it's on the border of light to dark), my headlights will be on for a while, turn off for awhile, turn back on for awhile, just repeating. I would guess each cycle is 30 seconds but it could be longer/shorter.

I never noticed this before. What can I check, is the only thing that it could be in my case is the sensor on top of the dash???

By the way, the auto lights work 100% at night and in the day, it's just on the border of dark/light I get the flashing headlights.

Hmm. Anyone had this problem?? I jsut wanted to know if I replace the photocell that someone did hte same thing and it fixed it. I hope it's not circuitry the photocell is connected to..........

 

My lights (as well as the lights on my brothers '07) flash on and off a couple times at dusk. They have both done the same thing since the day they were bought. It sounds like yours is doing it for awhile though, correct? Most of the time mine will turn on, turn off, turn back on and then stay on.

 

mine is an 06 and it has never done this until about a week ago, which is strange to me. Normally when the ambient light gets to a certain threshold the lights go on and stay on. To confirm I asked a guy with a mercedes and a guy with a dodge charger with auto lamps. Both of them say that there lights will not flash on/off at dusk.

I took a quick look at a headlight schematic I found online, it seems that the sensor on the dash has solid state control on it that probably controls when it goes on/off. The photo-diode on the dash grounds out a pin on the VSS module when it senses light, and the VSS module activates the headlamp relay.

I have to find a schematic of the photo-diode module on the dash, but I don't think I'll get that. From the little diagram I have it shows 2 photocells in there and a black box labeled "control solid state". I don't know what is in that box. I'm curious to whether the sensor on the dash has the filtering for on/off delay or if it's the VSS.

I'm going to the dealer tomorrow I'll check how much that dash sensor is, if it's cheap enough I'll pick one up.

 

maybe you just haven't noticed, my 06 has done this for as long as i can remember. driving around at dusk in lighter areas the lights will turn off and when going under trees and things in the shadows the lights turn on.

 

thats true, but I really don't remember having an issue with it before.

I did a little more research, apparantly the sensor on the dash has 2 photodiodes because it is designed that only if they both are activated the lights go on. One is set to go off at a higher light intensity to reduce the on/off condition so it has a band that it won't activate.

To me it seems like one of the two sensors is not working correctly or the electronics that compares the two is faulty. I'll just get a new sensor if it's cheap.

If that doesn't fix it then I'll live with it, no way I'm buying a new VSM module!

 

x2 If they work fine, I wouldn't spend the money to fix something thats not broke. But its your truck and your money. Just my $.02