Headlight selector on Auto, lights on and off when it's dark

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duckman820
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Joined: Mon Dec 02, 2013 12:43 pm

Headlight selector on Auto, lights on and off when it's dark

Unread post by duckman820 » Mon Dec 02, 2013 1:30 pm

I have a 2003 Saturn L 200. In the past month or so, when the light selector is in the "Auto" position and it is dusk or dark outside, the dash lights, tail lights, and front parking lights will start coming on and off. When I put the light selector in the other two positions, everything works properly. When it's daylight out, and the selector is in the "Auto" position, the daylight running lights work as they should. When in "Auto" and the ambient light gets dark enough, the lights switch over, but I have this issue with it seemingly wanting to go back and forth from daytime running configuration to night time. I'm guess it's a bad ambient light sensor, the little sensor that sits on top of the dash. Does anyone else have any ideas? Thanks.

 

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carriedi
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Re: Headlight selector on Auto, lights on and off when it's

Unread post by carriedi » Mon Dec 02, 2013 7:39 pm

Yes, you could have a problem with your ambient light sensor. have you tried covering the sensor up completely and see if the lights do the same thing as when it gets dark outside? The light sensor goes right to the body control module to control the lighting system.
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duckman820
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Joined: Mon Dec 02, 2013 12:43 pm

Re: Headlight selector on Auto, lights on and off when it's

Unread post by duckman820 » Mon Dec 02, 2013 8:13 pm

I have attempted to place items on the sensor, but apparently enough light still makes it through the covering that the sensor doesn't switch from daylight to night time driving. I suppose the next step is to cover the sensor with layers of electrical tape in an attempt to blacken it out.

duckman820
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Joined: Mon Dec 02, 2013 12:43 pm

Re: Headlight selector on Auto, lights on and off when it's

Unread post by duckman820 » Thu Mar 12, 2015 8:18 am

The sensor has been replaced and did not address the problem. I've been told it may be the control module, with some mechanics saying it may be possible to program the control module so that the lights work properly when the light selector is in the "Auto" position, or the control module is bad and I'll have to replace it.

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carriedi
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Re: Headlight selector on Auto, lights on and off when it's

Unread post by carriedi » Thu Mar 12, 2015 6:26 pm

you should have it scanned and see if there are any codes in the body control module. You could try switching the headlight relay with another like relay and see if that stops the problem.

Is it an intermittent problem or is it always not working? Always not working is much easier to find because you just look for what you are missing. No power or no ground, and where is the signal lost. Intermittent is much harder because you can only check for it when it is not a complete circuit.
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duckman820
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Joined: Mon Dec 02, 2013 12:43 pm

Re: Headlight selector on Auto, lights on and off when it's

Unread post by duckman820 » Sat Mar 14, 2015 8:36 am

The exact problem I have is, when the selector is in the "Auto" position, when I hit the remote to unlock the car the lights, as they should, come on. The taillights, however, flash on and off in a rapid, inconsistent pattern. When I start the vehicle, the headlights come on and stay on, but the dashboard lights do not. The taillights do not continue flashing. They simply do not come on at all, not even when it gets dark. I have adjusted the dashboard dimmer dial and that is not the problem, as far the dashboard lights are concerned. Another question about the headlights. The headlight covers are pretty clear. The headlights, the originals, when in low beam don't seem to be very bright. Do those headlights lose their intensity over time? Would replacing them make a difference?

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carriedi
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Re: Headlight selector on Auto, lights on and off when it's

Unread post by carriedi » Sat Mar 14, 2015 12:48 pm

daytime running lights, on some model cars, will only turn on the headlights with a reduced signal. Dash and parking lights are on the same circuit. They will not be turned on with with the DRL. (In the daytime, when it is light outside)

When it becomes dark, dark enough for the automatic lights to come on, the parking light circuit will turn along with the normal headlight power mode.

It sounds like your auto headlights are not working but your DRLs are. The automatic headlights (automatic lamp control, ALC) are controlled bu the body control module (BCM) You can scan the BCM for codes and/or look at the data stream to see if you can see a problem. If you can manually turn on your headlights with the switch and they work fine then I would look at your ambient light sensor circuit and the BCM. The ambient light sensor uses a light green and black wire at the BCM for the 5 volt reference out and it uses the yellow and black wire for the sensor return. Usually covering the sensor with an opaque material is enough to cut off light to the sensor and the auto lights should come on.
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