Brake lights not working?

Have you checked the bulbs? They are a double filament bulb. One filament is on when the lights are on and when you press the brakes the other filament lights up. This guide can help us fix it

https://www.2carpros.com/articles/brake-lights-not-working

Check that and if that doesn't work let us know.

I have attached the wiring info for the trailer wiring. In both it states the white is a ground wire. So it should connect to the frame. I can not see from your pic, but is there a bolt, screw or something right near the wiring harness within reach of the white wire? The end of the white wire looks like it was pull out of something if I can see it correctly. I would ground it and see your results.

Also, since you have now that you have what the wires do, I would turn the lights on, the blinkers, have someone hit the brakes and test the voltage coming in to the connector before the spice and after. If there is voltage in t he wires when the tests are being done before the connector, t then the problem is after the connector. If you dont have voltage even getting to the connector, then it is farther up.

Check out the diagrams (Below). Please let us know what happens.

I tried grounding the white wire before and now agian, both times it blew the fuze. There is a white wire to ground the trailer lights, which is still grounded properly. The white wire im dealing with is coming from the front of the truck.( before the trailer light harness) Using a test light, this white wire has power when the brakes are applied. This wire is also spliced into by the toppers third light for the power wire, there is a separate ground wire for the third light. I have went to the two salvage yards near hear to get a look at others wiring, and the trucks i have found (which were chevy's and gmc's from 92 to 95--mine is a 97) do not have this white wire coming from the front. It has got me very confused.

Okay, so that wire has been added or it seems like it has been. Have you always had this truck?. For now definitely tape it off so it doesn’t’ touch anything. Now what about the other thing I suggested checking?? See the above and lets check the other wires…….and tell me what you get.

Looking forward to hearing back from you……..

I Havent had the chance to test which wire is for what again, I will soon. I did use a test light and check the all the wires earlier. Each one worked for some source. They all worked before the trailer harness, after the trailer harness and at each taillight. of course except for the brake lights. The only wire that gives any power when the brakes are applied is the white wire coming from the front of the truck. This wire was not added by anyone, but appears to go nowhere. I will test what wire does each function tomorrow and also take some good photos if possible. Thanks for you help.

Hello –

Thanks for the info. It is important to chart it so you know that before the connector when you do this function, this color wire does this according to the info above. And then the same thing after the connector. I can not tell by the pic (thanks for providing that by the way) if you have a red 30 amp wire or a blue 30 amp wire feed. This tells us if you have the UY1 or UY7 towing package.

That is interesting about the white. It looks like according to the pic that the blue part it comes out of was a clamp on elec clip for wire splicing.

Might sound crazy, but both the towing packages, the yellow wire and the dark green wire control the left and right stop lamps. When you look at the wiring harness, does it look like that white wire pulled out of where those wires go in? From the pic again, to me it looks like it was pulled out of something.

My initial guess is if you took a wire and went from that white to the yellow and the dark green and hit the brakes, they would work. I would still like to know what happen there though.

You are welcome for the help.

Thanks agian, I will have some pics a documnet each wire agian in a few hours. (I was working on this a couple weeks ago and gave my mind a rest for awhile so i forgot which wire is which) When i was working on it i did splice that white wire into the left blinker and right blinker wires just to try it. What happened was, if the blinker was turned on, it would blink on both sides like a hazard light. And when the brakes were applied, the would work, but their was a clicking sound in the cab of the truck ( i think the relay switch)

This is a picture of the wires coming from the front end of the vehicle, ending at the harness. Coming from the front is a BROWN wire (tail lights) Yellow wire ( Left blinker) Light green wire ( Reverse Lights) Dark Green wire (Right Blinker) White wire (power when brakes are applied) and a ORANGE and a BLUE wire that loop and head back towards the front end (these are a much thicker gauge). In the picture you will see a blue splicer on the white wire, this is were the topper brake light is spliced in and works great. The wires going into the harness are: Brown=Lights Yellow= left blinker lt green = reverse dark green = right blinker Out of the harness are: Brown=Lights Yellow= left blinker lt green = reverse dark green = right blinker At the drivers side light: Brown = lights yellow = blinker lt green = reverse black = unknown (maybe ground) At the passenger side light: Brown = lights Drk Green = blinker lt gree = reverse black = unknown And with the trailer light adapter added into the harness, which we will just take out of the equation: Yellow = left blinker Brown = Lights Lt Green = Right blinker White is a ground wire for the trailer lights

Hello - I looked back on what we have talked about and I don't see where it was said if this is a 1500, or 2500 PU. Please let me know and the exact engine and the 8th letter in the VIN. Also, the pic you attached, thanks, but the wires with the red circle around it. That is hard to see especially with the splice. Going into the plug the first is DK Green, then Lt Green, then yellow, then what - this is all the confusion area for me to see. thanks

Into the harness is the Drk Green, Lt green, Yellow and then brown. Left to right. The white comes in the same bundle but im am clueless where it goes.

It is a 1997 1500 with a 5.7liter

And the 8th letter in the VIN is R.

Thanks agian for helping out.

Hello - Rossickle - may I call you that? Okay - lets do a recap please to ensure you and I are on the same. I don't know about you but it helps me focus since there are numerous posts between you and I, there is time lags inbetween and, I am dealing with other vehicles. 1997 Chevy Silverado, K1500, 4WD automatic, 5.7L VIN R, 220,000 miles Based off of the above post on which towing package you have - I would say it is the UY7, heavy duty. Would you? UY1 - wire colors - - Dark blue - 30amp auxiliary circuit - Brown - Tail and license lamps - Lt Green - backup lamps - (missing from the info provided by the dealer????) - Dk Green - Right turn signal and stop lamp - Yellow - Left turn signal and stop lamp - White - ground UY7 - wire colors - - Red 30amp battery feed - Dark blue - auxiliary circuit - Brown - Tail and license lamps - Lt Green - backup lamps - Dk Green - Right turn signal and stop lamp - Yellow - Left turn signal and stop lamp - White - ground What you currently have No brake lights on rear other than on topper. DK Green and Yellow - Blinkers - okay Lt Green - Reverse - okay Brown - Tail - okay I have attached a pic for you that I drew that shows your first pic - this is the wiring harness - correct -the color of the wires and what they go too? Please let me know if this is correct. The red X on the wires mean that from what I can see, those wires are not there. Also, the from the front of the truck, I left the white wire just sitting out there, is this correct? It comes from the front of the truck with the rest and is just hanging? The second pic you sent where all you have is the harness from the front of the truck, I sent back a circled area that looked confusing. 1. The white wire that I can see no insulation on that is coming out of a blue clip: a. Is this a spliced in wire? b. If so - what color wire is it spliced into? c. Is it hot at any time? d. Did you splice it in? 2. The white wire that is coming down from the front of the vehicle, I can not tell from the pics - what is it doing or where does the go or is it just hanging? 3. In your first pic where you show the complete harness, thee is a red wire that look like it is coming out of the middle part of the harness and plugged into the blue splice. Is this correct or what is going on here? A couple of checks also When you push on the brakes - the Dark Green and Yellow wire going into the harness - do they then have 12v but when no brake nothing? With the lights on - do the Dark Green and yellow have any volts? When you have the lights on and hit the brakes - then to the dark green and yellow have 12v Also on the pic that has the red circle on it, it looks like the wires from left to right are dk green, lt green, yellow and then the next hole is empty on the connector....is that correct? Last - they system was working...you have 200+ miles. Have you recently ran over something, when did you notice they weren't working? If you can answer these questions that would be great. Let me know what ever corrections I need to make. Bob

Hey one other thing.........when you turn your emergency flashers on - do the other lights act the right way ie the fronts flash etc?? If not change the hazard flasher and then check it.

Hello agian,

To start i would say i have the UY7 package. Because coming from the front end and looping back are both a Blue and Orange wire (says red on your diagram) The blue and orange wires have a tag on them that looks like it may say auxilary circuit.

Next, your diagram is correct. The white wire is just hanging from the front end.

Then,

The white wire has no insulation on the end of it. There is a blue splicing clip added to it.

Question 1
a. is this wire spliced? YES
b. If so - what color is it spliced into? RED ( this wire goes up to the topper light)
c. Is it hot at any time? When the brakes are applied
d. did you splice in it? The men who installed the topper did it. It was installed a year ago.

2. The white wire is just hanging it comes with a group of wires from the front.

3. Yes the red wire goes to the topper light.

I will get back to you with the voltage info for each wire. ( ineed someone to hit the pedal and switches)

Next,

When was it last working? I rarely drive this pickup (maybe twice a month) But it was noticed a few weeks ago. I have only drove it in town on pavement for the last year.

This is a drawing of where every single wire goes. I just hope it will be big enough to see.

Did you ever find the issue or fix to this problem? It's the only thing I can find that's the exact same problem I have?

I have the exact same problem, except my flashers do not work.
But not sure about the white wire.
I am replace flasher unit to start.

I'm posting this because no one posted the right answer yet. The most likely reason the brake lights are not working is the turn signal switch. I'm working late on the same problem and i can post more info maybe in a few days.

If the turn signals are working,check voltage coming out of brake switch. Sorry i don't have colors yet,but the wire from brake switch goes up into the steering column and feeds through the turn signal switch. The white wire coming out of harness is not the ground. I'm checking now to see what that is for. Hope that helps someone.

I haven't been on this site in a long time,so i don't know if we get email notifications when someone else comments.

I have the same white wire in my harness, and after hours of studying wiring diagrams I have figured out that it is for the CHMSL (center high-mounted stop light) at the top rear of the cab. Just in case anyone else is still trying to figure it out.

Excellent addition to this thread! Please feel free to help out whenever you are on the site :)

Currently I have no brakes lights, all other rear lights function properly. I have replaced the brake light switch and the multifunction switch in the column and have replaced the fuses with no success. However when I depress the brake pedal I can hear the under hood relay clicking so I know I have power at least to the switch.

Help if you can.

do the rear turn signals work? does the third brqke light work or are they all out?

Yes, turn signals work fine along with tail lights. There is no third light.

check for power at the white wire at the multifunction switch when pressing the brake. if no power then trace it to the brake light switch and repair the broken wire. get back to us if you need further help

I have power at the white wire coming from the brake switch, but not at the multifunction switch when I depress the brake.

the wire is probably broken AT THE solder joint, just run a new wire from white to white at multi function switch and you should be ok

1997 Chevy Silverado V8 Four Wheel Drive Automatic 220000 miles

My brake lights do not work. The blinkers, reverse and tail lights all work fine. I also have a topper on the truck, which the third brake light works fine. Coming from the front of the truck are 5 wires, Brown, Yellow, Dark Green, Light Green and WHITE. The white wire has power when the brakes are applied, but the white wire is not connected to anything. I dont know where it is suppose to go. The WHITE wire is spliced into for the third brake light( which agian works perfect) Anyone have the correct answer?

i have a 1997 chevy 1500 that i just bought a few months ago and my turn signals work but yet my brake lights dont what could cause the problem?

Does the high mount brake lamp work? If neither the high mount brake lamp or the lower brake lamps work, have to check stop lamp fuse and stop lamp switch.

wheres the stop lamp switch at?

The switch is activated by the brake pedal arm, follow the brake pedal arm, you should find the switch. In the diagram posted, did you check for voltage at the stop fuse?

iv already replaced that switch n still nothing

Did you check voltage to and from that switch, I gave you the wiring colors. Is the switch adjustable, anyway? Can you use a jumper on the proper wire colors and bypass the switch, just to see if brake lamps will work? Of course that proper wire color in diagram, on top. has to have voltage, for the jumper to work.

My truck has tail lights and turn signals, but no brake lights. The fuse is ok. What else can I check? Where is the brake light switch?

I found the above info for removal. Does the highmount brake lite work? The orange wire is feed to the brake switch, hot all the time. White wire is the feed coming from the brake switch to brake lites, that wire should be hot when you step on the brake.

I have same issue as rossickle. Mine is 94 3500 2wd. Spliced into turn signals, the white brake wire correctly opperates brakes lights. BUT it overrides the turn signals, so it's not a fix. Drove it yesterday like that and got a warning ticket for no turn signals. Frustrated.

It looks like the white wire goes to the high mount brake light relay, here are the wiring diagrams for the system so you can see how the brake light works. Also, here is a guide that might help as well:

https://www.2carpros.com/articles/brake-lights-not-working

Check out the images (below). Please let us know what happens.