auto headlights?
 

Anyone out there know if there is a way to disable automatic headlight function? Even when the headlight selector is in the off position, it seems they are always on auto-mode based on the sensor on the dash.

Having had the car a couple weeks now - it seems to me this feature is overly sensitive. ex; headlights can come on just from driving under the shade of an overpass in broad daylight. Or every time I drive in to my garage.

(not that they actually provide any light!!)

Seems like it is a Canadian market thing based on what I've found in the owner's manual, but curious if there is a fix.

Thanks!

I believe Canadian law requires that Daytime Running Lights be on all the time, whereas optional in the US,although I don't know if this applies to mid-'90s car.. I also don't know if DRLs in Canada mean the full headlights are on--usually they use lower brightness lamps. --Bob

Canadian law did require DRLs at the time this was produced, and it is often high beams at half power. On the C4 they actually use the turn signals staying full on.

The DRL's and headlights seem to operate under the same light sensor system.

When the parking brake is released, DRL's go on as long as the light sensor detects light and the light switch is set to off.

When the sensor finds low light and it will turn off the turn signal DRL's and open up the headlights regardless of the position of the light switch. And it doesn't take much low light to force the headlights on.

Would prefer to control the headlights manually but that doesn't seem to be an option.

I would think that you could add a manual switch in the E-brake circuit to make the DRL module see E-brake 'ON'. That switch would allow you total manual control, I'd think.

What year car and do you have the FSM yet?

it's a 1991 and I received an FSM from previous owner .....

Spend some time @ 8A-104-0 & forward in the electrical section to review the actual operation, wiring and diagnostics. I believe a 'talented' person could create a situation/operation that suits you. Simple? Unlikely but I imagine quite possible. 8A-201-15 might be of interest also. The actual module is the same all years but wiring would change year to year.

8A-201 section of the FSM has much very good info for a C4 owner.

***The DRL also won't function with less than 9V or greater than 18V so you might be able to figure out how to control voltage. to it. Might be an interesting adventure!

If you don’t already have it, you will need the 1991 Electrical Diagnosis Service Manual supplement that WVZR-1 is referring to. If you get into anything electrical or electronic on the car this manual is invaluable.
H
:cheers:

oof --- ok it might take some time for me to work up the 'talent' to tinker with this.

I don't seem to have a section 8A supplement manual. Only the standard FSM ---- there is some general info about the light sensor in 8B and 8C, but nothing about diagnosis. Suppose it is something I can live with.

Turns out the DRL sensor isn't the thing I thought it was so at least I learned something! It's located in front of the steering wheel (Canada only), not the "sunload temperature sensor" in the center of the dash pad.

There is no DRL sensor. The sensor you speak of simply controls when the headlights are triggered to turn on automatically (Canadian thing on 91 and up Zs). My 90 has DRLs - they are not simply the running lights being turned on - that is too dim. They are the same as the intensity when the turn signal is at the highest level during operation - but all the time. They turn on when the parking brake is released.

To defeat the auto function, remove the light sensor (on the dash in front of the steering wheel), and insert something (a penny works well) to complete the circuit, but tells the BCM that there is intense light at all times, therefore keeping the headlights off.

Dirt cheap solution - enjoy!

excellent! thanks for that. Seems the hardest part is finding a penny!

Is there any way you can describe or post of a picture of how you apply the penny in the sensor? I have a 1992 and I'm attempting to disable the auto lights function.

Ok. So right after I asked you to add a description or a picture, I went to the garage and tried a penny at 1st. Too big. So I just found a thin piece of metal that would fit down in there where the sensor once was. I did not disconnect the battery. No issues with anything. Turned off the lights in the garage just to make sure it was dark enough. Started the car, released the emergency brake and the lights did not come on in a pitch black garage. The lights only came on when I turned the knob. The also turned off like they were supposed to. This was the easiest fix ever. The cover for the sensor fit right back over these pieces of metal and it went right back down in the dash. You can not tell the difference. All you do is pull the blue looking sensor out which is basically like a fuse, and replace it with any piece of metal. This is on a 1992 LT1 Corvette.
https://cimg4.ibsrv.net/gimg/www.cor...48342c5915.jpg
1992 C4 LT1 - Headlight sensor replaced with random piece of metal.

Good news! That sure beats pulling the emergency brake just enough to keep the lights off but not engage the brake!

Does the sensor assembly just pull right out from the top of the dash?

This thread has been helpful to me. How do you remove the blue lens without destroying it? I'm assuming you just need to get something metal across those two little terminals on the actual sensor?
https://cimg0.ibsrv.net/gimg/www.cor...aae41cbedc.jpg

Yes, that whole piece just comes out. Softly push down on the area around the black sensor sitting down in the dash and just use your fingers to pull up on the black enclosure until it comes out. Once out, twist off the top of it will a slight twist. Then the blue sensor the top just comes out just like a fuse. Just carefully pull up on it. All you have to do is find a thin piece of metal that will fit firmly in there. When you are done, you will not put that blue sensor back in. Just keep it encase you want to convert back. .

:cheers:

I’m no electric guy, but you probably could. I read some where that all you need to do is complete the circuit. So if adding a jumper from red to green completes the circuit, I think your good to add a jumper and all should work.

Sticking a piece of metal in there worked perfectly, thanks for the tip! I ended up using a washer that fit right in, so yes as long as you complete the circuit, you will have bypassed the auto feature.

hahahaha. just want to thank the OP for posting his solution. and his followup. im finally getting my car to the track tomorrow and really didn't want to drive around with my headlights up. problem solved. cheers.

edit: what i ended up using was a mini fuse with the metal tips folded back over to double up the width of the metal prongs. fit perfectly. even blue!

This may be a stupid question but can't you just cut the 2 wires that connect the sensor?