Getting manual control of headlights

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Oct 14, 2021
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I hate the stupid auto headlights on my C7 ZR1. I hated it also on my C6 Z06 but on the Z06 for example if I drive it into my garage I at least get 30-40 second delay before the lights will come on. That gives me enough time to shut off all the accessories in the car etc etc etc before I shut the car off.

On the ZR1 I don't even get to take a second breath once I pull into the garage the hdlts come on IMMEDIATELY. I kinda want to know if anyone has a way on the C7 to disable the auto headlights so I can turn them on when I want them on. Any ideas???? Is there a fuse I can pull or some minor thing I can do to achieve this?

I've read about getting a GM dealer to reflash the BCM to a different setting that will give me back control of the headlights but the chance of a dealer doing this for you is next to nil.

Like to hear some input on this.

Tony
 
I've been interested on doing this on my poor mans base stingray too haha. I love the DRL led look and would like to be able to keep it on longer but haven't been able to find any info on the forums. Fairly surprised actually I figured there would be a lot of people wanting this function.
 
Drove my car yesterday early morning 7am to about 8:30am, of course the hdlts were on but what really annoyed me was nearing 8:30am almost home lights were still on but sun is up and not dark anymore. That's messed up.

I just looked in my OM it doesn't show a fuse for auto hdlts or something like that. In the engine compartment fuse box there is a low beam hdlt relay in K21 along with fuses 83,84,85 (L. Hdlt, R Hdlt, and high beam hdlt respectively).
 
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Canuck204 said:
I've been interested on doing this on my poor mans base stingray too haha. I love the DRL led look and would like to be able to keep it on longer but haven't been able to find any info on the forums. Fairly surprised actually I figured there would be a lot of people wanting this function.
Click to expand...
I believe over on the other forum our US counterparts were able to find a way around it, but only on US built cars; due to our regulations up here don't think its possible unless you got a tune possibility with that included perhaps?
 
So my visit to the dealer near me was a waste of time (I knew it going there but worth a shot). They didn't want to provide the wiring diagram for me and I kept getting the crap about government mandated stuff blah blah blah and GM will not disable these features.

Yeah they just want me to replace light bulbs at $200-300 per if they are always coming on and going off repeatedly etc etc.

SO.........................came home and was able to find online the SM for a 2014-2017 C7 Corvette, the wiring for the lights should be the same so at least I was able to see the diagram and I have some ideas on what to do. Easiest is to mod the light sensor so it fools the BCM into thinking it is daylight all the time and that would keep the lights off till you turn them on with the switch. The only thing I'm not sure off is the fact the sensor is kinda tied into the HVAC system where if it senses major daylight heating up the interior it causes the HVAC system to attempt to offset that by diverting cool (AC) air thru the vents (cooler than the set temp???? Not sure on that) so there is some research there to make sure not to mess up the HVAC part of the sensor system.

Probably a good idea to get a spare sensor and mess with that till I get the right result before I dive into messing with the one on the dash........................stay tuned.
 
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Afterimage said:
So my visit to the dealer near me was a waste of time (I knew it going there but worth a shot). They didn't want to provide the wiring diagram for me and I kept getting the crap about government mandated stuff blah blah blah and GM will not disable these features.

Yeah they just want me to replace light bulbs at $200-300 per if they are always coming on and going off repeatedly etc etc.

SO.........................came home and was able to find online the SM for a 2014-2017 C7 Corvette, the wiring for the lights should be the same so at least I was able to see the diagram and I have some ideas on what to do. Easiest is to mod the light sensor so it fools the BCM into thinking it is daylight all the time and that would keep the lights off till you turn them on with the switch. The only thing I'm not sure off is the fact the sensor is kinda tied into the HVAC system where if it senses major daylight heating up the interior it causes the HVAC system to attempt to offset that by diverting cool (AC) air thru the vents (cooler than the set temp???? Not sure on that) so there is some research there to make sure not to mess up the HVAC part of the sensor system.

Probably a good idea to get a spare sensor and mess with that till I get the right result before I dive into messing with the one on the dash........................stay tuned.
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Doubt you will have much luck with the light sensor. Had a problem on a Grand Prix way back when. The lights would come on in full daylight. Had to put a kleenex over the sensor to let some light through but not full spectrum. They changed out the dash sensor. Full lighting worked in twilight as well.
At any rate it is a light sensing diode that is calibrated for particular lighting scenarios. Unless you can change out the diode or somehow put a pot on it you'll have to suffer the settings as is..
 
If you are into electronics soldering a diode is no big deal. There are a bunch of things I still have to figure out such as what voltage that diode will generate when there is sunlight vs. no light and whether another photo electronic diode is available that will only generate the voltage needed to keep the hdlts off after it's installed and again the HVAC issue.

I have a movie date later today so on the way to the theatre I'm dropping by the dealer again to check on the sensor (and probably order one for me to mess with).

I had the same BS issue with my new at the time 96 Pontiac Formula but on that car it was easy to access that sensor (that was a variable resistor based on light input). I measured the resistance when sunlight was on it vs. not and removed the factory resistor and installed a regular resistor with the proper ohm reading that kept the lights off till I turned them on with the switch. That car was even worse with the pop up lights I would get fuel at the station and was parked under the roof thing gas stations have. It could be the middle of the day and after I was done start up the car and the lights would pop up and come on........................like WTF?????

Here's the wiring diagram (again for 14-17 cars, should be same for 18-19) and that sensor is a photo diode. In the diagram look at B10B Ambient Light/Sunload sensor that is the round little bubble thing on the top of the dash in the middle. Once I get a spare one I have to power it up with 5 volts (according to what I've been reading in the manual) then measure the voltage it generates when light is shining on it (anywhere from 0.4V - 5V) and when it isn't. Once I know that voltage # with sunlight on the sensor find a similiar diode that generates the same voltage on its own and replace and that should keep the lights off. To not mess up the HVAC part of the system I might find a diode that generates a lesser voltage but enough to still keep the lights off and that should do it. ALA a fixed voltage generating diode is available (not sure on that yet) it should be quite doable (if not a tad labour and $$ intensive).
 

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I would check the rest of the wiring diagram right back to the headlights. Based on what I can see in these two diagrams it is only sharing a common ground with your HVAC and theft deterrent. It is not supplying anything else from what I can tell.
 
Afterimage said:
If you are into electronics soldering a diode is no big deal. There are a bunch of things I still have to figure out such as what voltage that diode will generate when there is sunlight vs. no light and whether another photo electronic diode is available that will only generate the voltage needed to keep the hdlts off after it's installed and again the HVAC issue.

I have a movie date later today so on the way to the theatre I'm dropping by the dealer again to check on the sensor (and probably order one for me to mess with).

I had the same BS issue with my new at the time 96 Pontiac Formula but on that car it was easy to access that sensor (that was a variable resistor based on light input). I measured the resistance when sunlight was on it vs. not and removed the factory resistor and installed a regular resistor with the proper ohm reading that kept the lights off till I turned them on with the switch. That car was even worse with the pop up lights I would get fuel at the station and was parked under the roof thing gas stations have. It could be the middle of the day and after I was done start up the car and the lights would pop up and come on........................like WTF?????

Here's the wiring diagram (again for 14-17 cars, should be same for 18-19) and that sensor is a photo diode. In the diagram look at B10B Ambient Light/Sunload sensor that is the round little bubble thing on the top of the dash in the middle. Once I get a spare one I have to power it up with 5 volts (according to what I've been reading in the manual) then measure the voltage it generates when light is shining on it (anywhere from 0.4V - 5V) and when it isn't. Once I know that voltage # with sunlight on the sensor find a similiar diode that generates the same voltage on its own and replace and that should keep the lights off. To not mess up the HVAC part of the system I might find a diode that generates a lesser voltage but enough to still keep the lights off and that should do it. ALA a fixed voltage generating diode is available (not sure on that yet) it should be quite doable (if not a tad labour and $$ intensive).
Click to expand...
Not in to electronics like you are but is there not just a simple way to disable the command signal for the lights only and leave the HVAC system on line. Obviously some place after the diode. Optional is to run a line from the light control direct to your lights. Probably need a three position to keep the daytime running lights.
 
12cents said:
I would check the rest of the wiring diagram right back to the headlights. Based on what I can see in these two diagrams it is only sharing a common ground with your HVAC and theft deterrent. It is not supplying anything else from what I can tell.
Click to expand...
Would concur with your comment 12. Looks to me like the diode just send more or less current off to the grd. If a pot (non smokable) can be put in line it would allow manual adjustment
 
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I appreciate the comments. A friend of mine is more into electronics than I am (I'm kinda savvy with it to a point). I obviously am not going to majorly mess with this until I know what I can do. Getting a spare sensor to start gets me in the right direction to research and experiment before screwing around with the hdlt wiring in my ZR1, a car that I don't want to mess up on. So again I'll just say stay tuned and I'll share what I find out as I go.
 
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Afterimage said:
So my visit to the dealer near me was a waste of time (I knew it going there but worth a shot). They didn't want to provide the wiring diagram for me and I kept getting the crap about government mandated stuff blah blah blah and GM will not disable these features.

Yeah they just want me to replace light bulbs at $200-300 per if they are always coming on and going off repeatedly etc etc.

SO.........................came home and was able to find online the SM for a 2014-2017 C7 Corvette, the wiring for the lights should be the same so at least I was able to see the diagram and I have some ideas on what to do. Easiest is to mod the light sensor so it fools the BCM into thinking it is daylight all the time and that would keep the lights off till you turn them on with the switch. The only thing I'm not sure off is the fact the sensor is kinda tied into the HVAC system where if it senses major daylight heating up the interior it causes the HVAC system to attempt to offset that by diverting cool (AC) air thru the vents (cooler than the set temp???? Not sure on that) so there is some research there to make sure not to mess up the HVAC part of the sensor system.

Probably a good idea to get a spare sensor and mess with that till I get the right result before I dive into messing with the one on the dash........................stay tuned.
Click to expand...
You could find the headlight fuse and use a remote controlled switch inline with it. Similar to how a mild to wild remote works. That would likely work and give you the option to switch it back to normal operation anytime.
 
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FYI this is what happens when you pull circuit breakers on equipment with serious computer integration. Air France A320, 1988. Pilots pulled some CB's to disable some of low level terrain avoidance warnings, and when they went to do the go-around the computer said "screw you".

Play with fuses and circuit breakers at your peril.....



PS: Great thread hijack.....
 
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