Head Light On The Time

[POP'S TOY]

I hope someone can give me a idea of what may be wrong with my headlights and how to fix this problem.

I bought the truck about 3 months ago and it was like this when I got it. The vehicle is a 2001 Chevrolet Silverado and the head lights (all lights are on, taillight & dash lights) are on as soon as you turn on the key to start the truck. The Day Time Running lights do not work and the map/temp is in the dim mode all the time due to the lights being on I guess.

It looks like all the wiring for the headlights under the hood has not been messed with. No wires appear to have been cut or replaced.

Thank you for any and all the help.....:(

[DmaxMaverick]

Welcome aboard!

Check the daylight sensor, and associated wiring. The sensor is a dark colored, marble-size dome, located on the center of the dash, just rear of the windshield. If it's obstructed or failed, it will make the BCM "think" it's always nighttime.

[POP'S TOY]

DmaxMaverick DmaxMaverick

Thank you for the fast response. I check as you stated and there is no daylight sensor on the dash, I know what your taking about as there is one on my Ford Explorer. It looks like the mirror may have the sensor located in it. But it's not covered and clean as far as I can tell.

In my other comment I stated the truck was a 2001. I double checked as that just didn't set with me and found it a 2000. Just maybe this will help and not messed things up to bad.

Again, thank you for your help....

[More Power]

I hope someone can give me a idea of what may be wrong with my headlights and how to fix this problem.

I bought the truck about 3 months ago and it was like this when I got it. The vehicle is a 2001 Chevrolet Silverado and the head lights (all lights are on, taillight & dash lights) are on as soon as you turn on the key to start the truck. The Day Time Running lights do not work and the map/temp is in the dim mode all the time due to the lights being on I guess.

It looks like all the wiring for the headlights under the hood has not been messed with. No wires appear to have been cut or replaced.

Thank you for any and all the help.....:(

The sensor has to be there - on the dash near the defroster vents. If it's covered up, like DmaxMaverick mentioned, the computer will assume it's dark outside.

Mornings/evening during wintertime, dark cloudy days or even dense fog during the day can cause the lights to be on. You can over-ride the auto lights by pressing/depressing the round button on the light switch panel.

The daytime running lights (DRL) use bulbs that don't last long. So, your DRL bulbs are likely just burned out. Mine have been for a few years now. You can get lower wattage bulb replacements or even LED replacements that last longer.

Wlecome to the board.

Jim

[DmaxMaverick]

It's not in the mirror. If the mirror is electrochromic (automatically darkens), it only affects the mirror.

If the truck has auto-headlamps, the sensor will be on the dash as I described. If it doesn't have that feature (almost all models do/did), then the problem is likely the headlamp switch (not uncommon). The switch isn't too costly (anywhere but the dealer), and very easy to replace. What trim level is this truck? Basic "work truck", or upper trim? Power door locks and windows? Any trim level above the most basic should have the auto headlamp system.

With the key on (running or not), press the dome-override button (on the headlamp switch) quickly 4 times. If it chimes, it should disable the "night mode", the dimmer lamps should go to day time mode and headlamps should turn off. If it doesn't chime and the lights don't change, either it doesn't have the auto system, or the switch is bad.

You can also test this by applying the E-brake prior to turning the key to on. The headlamps should not come on if you have the auto system.

[chessy56]

Like Maverick stated: If your truck has a push-button dome light control (next to the head lamp switch), you can toggle this pushbutton switch 4 times and the lamps should switch to an over-ride mode that forces you to turn the head lamps ON manually if you want them ON. The interior "chime" should sound each time you activate/deactivate the over-ride mode. At least that's what I've found on my '01 Silverado.

I use the over-ride mode often at night so I can flash the head lamps and signal tractor/trailer operators when they've cleared my front end during crappy driving conditions.

[DmaxMaverick]

Correct, Chessy, although it only works when the key is on, and will reset as soon as the key is cycled.

Now that I think about it, you MUST have auto headlamps. Otherwise, they headlamps wouldn't come on at all when the engine is started.

OK. Go back to the previous posts and start there. If there is no daylight sensor in the middle of the dash, that may be the problem: it's been removed and not replaced. As More Power said, it's located at the inner end of the defog vent.

If testing of the E-brake and dome-override disable features (independently) works, the sensor will be the problem. If the testing fails, it's likely the headlamp switch. If the switch is rotated to "ON", the BCM cannot command any control of the headlamps, so if the disable feature is not working, the switch is suspect. If you have access to a Tech II scanner, you can read the actual BCM values of the sensor during daylight, covered and uncovered, and if it's present at all. The sensor function itself is a simple photocell.

[More Power]

With the key on (running or not), press the dome-override button (on the headlamp switch) quickly 4 times. If it chimes, it should disable the "night mode", the dimmer lamps should go to day time mode and headlamps should turn off.

It only takes two presses on my 2001 and Lil Red.

Jim

[DmaxMaverick]

It only takes two presses on my 2001 and Lil Red.

Jim

Mine does that too, sometimes. 2 "short, quick taps", will often do it, but they aren't full pushes, and the dome lamp doesn't turn off unless the button is pressed nearly all the way, like a ball point pen. The manual says 4 presses. I haven't disassembled my switch to find out why, but it isn't broken (it might be if I disassembled it). I stop pushing when it chimes.

[POP'S TOY]

Thank you for the advice. I tried that and yes it did turn off all the lights as you said it would. Now I just have to find out what the problem may be.

I was wondering if its not the auto sensor it may be in the light switch, which I have another one of from a junk yard to try.

Again, Thank you for the help I will let you know what happens when I do change the switch..:)

[DmaxMaverick]

If you are able to turn off the lights by BCM command (button pushes or E-brake), then the switch isn't likely the problem. I suspect a problem with the light sensor, or the circuit. If you have another headlamp switch, there's nothing wrong with testing with it. They're so easy to R/R, there's no reason not to.

If you are still unable to locate the light sensor, it's possible it has broken off (and possibly fell into the defog vent), or loosened, which could certainly explain your issue. In any case, you should be able to locate the mounting hole where it "was".

Looking at the electrical diagram:
The sensor is unique to the BCM. Meaning, it only connects to the BCM, and connects with nothing else.
The gray wire is a 5V signal from the BCM, and the white wire is the return signal (light condition indicator) back to the BCM.

Looking at the repair diagram/instruction, it is possible the sensor can "fall" into the dash. It's held in place like an instrument lamp socket, requiring only 1/4 turn to R/R it. It installs from the underside of the upper dash cover, and appears it could be loosened and fall into the dash (leaving it in the dark, all the time). Some instrument panel disassembly is required to access the mount from underneath.

Ultimately, whether you fix it or not, the auto-headlamp feature can be disabled in the BCM (eliminating the need for the sensor). I don't recall if it's a user-selectable option, or if a scan tool is required. I remember having this discussion before, but it's been several years.

[POP'S TOY]

I was able to turn off all the lights by the method you told me about. Also I think I found the hole in the top of the dash you also mentioned. The senor is not there so I guess it's gone or fell down inside. Now, I guess the work begins to get into that location and find or replace the senor.

Thank you for all the help and I will let you know what I find....

:):)

[DmaxMaverick]

The sensor is a 1/4 turn to lock, so it may be possible to loosen it from the top, allowing it to fall inside. I don't really care to try it, or mine might end up just like yours. Disassembly of the dash is fairly simple. Most everything is modular, and you may not have to take it all apart. If you can get a hand inside once the bezel and facing components are removed, it may be more simple than it first appears. I suggest pulling the airbag fuse before getting into it, just in case. Good luck!