Automatic Light Control Issue (Auto Lamp Control)

Yep, this is a problem with the photoresistor (ambient light sensor). I would try to find a used on on ebay. That should fix the problem.

Thanks for your feedback.
May you also let me know how to remove the sensor?
I don't want to break anythng on my dash.
The sensor is not directly visible at the front of my dash.
Is it below the grille? Do I need to remove the grille close to the windscreen?
Any screws to remove?

This is the PN I found:
Sensor - GM (10067986)

Unfortunately not listed on Ebay right now. Is there maybe another PN from a GM vehicle I could use as well?

You are correct, the sensor is in the front of the car just behind the grill, so no need to worry about breaking anything. Here is the location, also you have the old part number here is the replacement

GM 12450121 - “Sensor Assembly, Daytime Running Lamp Ambient Light.”

Check out the images (below). Let us know what you find.

Are you sure the part fits my 1997 GA?
I looked it up and it shows to fit a GA from 1999 to 2005.

GM (10067986) I found suits the 1996 to 1998 and this one is nowhere to find.

Please have a look at my Dash (picture attached). The sensor is not visible.

Do I need to remove the grille close to the windshield?

Also, may you have a Wiring Diagram of the ALC System?

Could I (worst case I cannot get a new sensor) disable the system?
Maybe to remove the ALC Relay in the Front Crash bar?

So the sensor is up by the grill (front bumper area) and you can use the part# I sent you which is just a newer version. If you unplug the sensor the system will be bypassed

Thanks, but now I am a bit confused. The sensor is not within the cabin (dashboard), but outside near the grill? Do I have to open the hood to see the sensor? And then close to the two grills I can see the sensor?

Yes, yes, and yes. It should be bolted to the center core support.

I just searched for the sensor under the hood but could not find any light sensor.

I then took my flashlight and looked for the sensor inside the cabin at the front of the dash.
Most probably I found it.
It is burried under the Windshield Defroster Vents Grill.
You can only see it if you use your flashlight from outside the windshield and point it towards the airvent grill.
See the attached picture I have taken from an Online Parts Catalogue.
It does not sit directly in the middle of the grill but a bit more to the passenger side.

If this is the sensor then I would need to remove the airvent grill and I don't know how to do it without breaking any clips.
Even if successful there is absolutely not much space to remove the sensor since it is half an inch below the grill and the windscreen is more or less directly over it.

This could become a nightmare t replace.

Hmm, looks like I got some bad info sorry about that. Yep you found it. It should just pop out of there, it is not held in by much. I would try to remove the vent which should help you gain access.

May you also have the Wiring Diagram of the ALC System showing the sensor and relays part o the system?

Yep, here is the wiring diagrams so you can check it out and see how the system works. Check out the images (below). Please let us know what happens.

Thanks very much.
Do I understand correctly.... the Instrument Cluster itself controld the ALC as well as the DRL?
There is no BCM or Light Control Module used for that in my 1997 GA?

So to check any Pins I nede to remove the Instrument Cluster (Spedo, RPM, Temp Gauge, ...) beeing able to disconnect the connector to measure any signal?

That is correct, the sensor goes into the instrument cluster. What are you trying to test?

I thought that it might be easier to deactivate the ALC by removing a Pin from the BCM but since it is connected directly to the Cluster I think it is not a good idea.
Removing the Cluster I guess is quite complicated.

reason for asking is that I cannot get to the Light Sensor. It is burried too deep in the dash. I cannot get too it since the space to the windshield is marginal.

I thought maybe removing the ALC relay could also work.

Yep, that can be a tight fit but you should be able to get a small standard screwdriver to help pop it out of there? Can you upload an image close up of the sensor so I can see?

Here is the image.
There more or less no space .
The problem is that on top of the sensor there is a round shaped plastic clip on top what has to be removed first before accessing the sensor.
And this plastic clip is approx half an inch below the vent grill.

Yes that is the vent grill, you should be able to remove the whole grill piece in one go, look for screws but if you cant find any it should just pop out of the there because it uses clips, let me know.