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Discussion Starter #1
my 2016 silverado is having issues with the brake lights....they will randomly come on and stay on for no reason. Driving down the road or parked at home at 2am they will just come on. I have asked people and they advised me to change out the brake lights switch...I replaced the switch and all was well for about 2 weeks then all of a sudden the lights will come back on for no reason. I got to work this morning and got out of my truck and they was off then when i closed the driver side door they came on again. Im getting a little tired of having to take my battery cables off to keep from running my battery down....can someone please help me????
 

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I don't have a wiring diagram for your 2016; but the Body Control Unit controls the lights.
When the signal to turn on the brake lights is received by the BCM, it electronically switches 12volts to the lights.

Most of the input signals are applied grounds, the BCM see a ground on the brake light switch circuit and turns on the lights.

Using that logic, I'd look for a bare wire touching the body metal somewhere around the brake light switch.
 

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I will do that on my next day off due to I work from sun up to sun down and thank you very much for your information. I have also recently found out that I have a recall on my truck dealing with reprogramming the computer dealing with my brakes...I wander if that may have something to do with it??
 

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Discussion Starter #4
I don't have a wiring diagram for your 2016; but the Body Control Unit controls the lights.
When the signal to turn on the brake lights is received by the BCM, it electronically switches 12volts to the lights.

Most of the input signals are applied grounds, the BCM see a ground on the brake light switch circuit and turns on the lights.

Using that logic, I'd look for a bare wire touching the body metal somewhere around the brake light switch.
Well after work Saturday 4/4/20 I got under the dash of my truck with my handy dandy flashlight stick and inspected everything I could see as far as wires go and I could not find any wires that appears to look bare or to be grounding out anywhere. I have not taken my battery cable off since the day of my original post and my lights have not came back on yet...YET!!! they just do it at random times out of the blue. I even got under the back of my truck and inspected the tow package trailer wires and plug thinking "ok maybe it could be this area" but did not see anything there either. :mad::mad: All of the electronics in today's vehicles are ridiculous, even found out my truck does not even have a throttle cable its all electronics.
 

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Discussion Starter #6
Yep, Drive By Wire.

Did you take a good look at the brakelight switch connector?
Yes I did and did not see anything under the dash out of place or out of the ordinary. This is really getting on my nerves cause for the past 2 days my lights have not turned themselves on at ALL till this morning when I got to work. I pull in the parking lot and turn my truck off and when i close my door and hit the lock button the lights came on and stayed on...i open my door and crank the truck...press the brake pedal and then let off...turned truck off and closed my door and locked it and they did not come back on.
 

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If they're going out when you touch the brake pedal, the problem has to be right there
 

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If they're going out when you touch the brake pedal, the problem has to be right there
Not when I touch the pedal but fully depress the pedal and let off like when driving. I can let off the pedal and they go off like normal but at times they come right back on when I close my door and don't even have to hit the lock button they will come on. It is very aggravating...lol
 

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Doesn't mater if it's a touch, or a full depression; if the problem goes away when you use the pedal, the problem is associated with the brake switch
 

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I. Got 99 gmc 1500 doing the bout same but when I push pedal down and when pedal coming up light go off for sec tell pedal all way up light coback on I put 2 new break light switch on it and new pigtail light still on could the blinker switch b the problem
 

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Discussion Starter #11
I. Got 99 gmc 1500 doing the bout same but when I push pedal down and when pedal coming up light go off for sec tell pedal all way up light coback on I put 2 new break light switch on it and new pigtail light still on could the blinker switch b the problem
sound like we are having some issues here!!!
 

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Discussion Starter #12
Well I took my truck to the dealership about my recalls and told them what my brake lights are doing. They looked at me like I was crazy and the tech told me if my truck is turned off there should be NO power goin to my brake lights due to its all computerized now days. He found some old codes in my BCM and cleared them out and said if it does it again bring it back and he would see if it threw a code out. I leave the shop and go home and be dammed if it didnt do it again so I took it back the next morning and he checked and it didnt show anything then he told me with a new brake light switch that he had the BCM learn the brake position again. Well I get home home and it did it again but did not stay on it just flickered so now he telling me im gonna have to drop it off for a few days next week and he may have to change out the BCM.....OMG this truck is getting on my nerves!!!
 

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H, I'm not going to say the tech is wrong because I've not played with any '16 trucks; but to the best of my knowledge, brake lights will light whenever the brake pedal is pushed, key on, or key off.

And to recap, the truck computers are now the switches that turn lights on and off, the switches at places like brake pedal arms are input sensors.
When the pedal is pushed a switched ground is sent to the BCM, receiving it, the BCM turns on the brake lights.

Now, at this point I want to clarify that switched grounds are the usual inputs, I do not have a wiring diagram for your truck and it is possible that your truck switches 12v to the BCM

Computers fail; but BCMs are pretty tough, I doubt that you have a bad BCM.

As I said in previous posts, you have a bare wire shorting to ground somewhere near the brake light switch, if the pedal switch provides ground.

If the pedal switch provides 12v you could have a short to some other 12v source.
 

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Discussion Starter #14
I do appreciate your input and if my lights continue to do what they have been doin I am going to drop it off at the shop and the tech can keep it till he figures it out or the dealership i bought the truck from can have it back due to this is some BS and should not be having this issue with such a new truck
 

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H, I've been thinking about your problem.
Does your truck use the same bulbs for stop and signal?
If it does, maybe the problem is with the signal light circuits.

When you have this problem, does the cab center stop light come on?
 

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Discussion Starter #17
H, I've been thinking about your problem.
Does your truck use the same bulbs for stop and signal?
If it does, maybe the problem is with the signal light circuits.

When you have this problem, does the cab center stop light come on?
Yes all 3 lights come on and it is getting very aggravating cause the tech that I talked to does not seem to know the cause other than saying the BCM may be having problems cause he has looked under the dash for bare wires and can not find anything.
 

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Yes all 3 lights come on and it is getting very aggravating cause the tech that I talked to does not seem to know the cause other than saying the BCM may be having problems cause he has looked under the dash for bare wires and can not find anything.
the GM dealership technician is lying to you about the brake lights coming on, when the ignition switch is off.. brake lights turn on when no key in the ignition switch when the brake pedal is pushed down lamps turn on all the time. now this is another GM wiring problem china crap. the brake pedal switch could be broken or the switch fingers broke down.
you can do the test. park the truck in a spot where you can see the brake lamps turn on when your in the driver seat. key off .. work the pedal a few times see how the brake lamps work all the same. another problem could be the brake pedal could drop slowly possible a master cylinder problem or some other issue causing the brake pedal to drop.
the other common problem can be adjust the brake switch so it will not turn on when you push the pedal down very slightly.. tap the brake pedal lightly see if the lights come on then adjust the switch.
 

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Discussion Starter #19
how can you adjust the brake switch? When I installed it it only has 1 small bolt to hold it into place and I can not tell how to adjust or move it.
 
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