Baffled By Brake Lights 03 gmc sierra 2500HD

[TBeast2500HD]

I have a 2003 gmc sierra 2500HD

i am totally ballfed as to why i have no brake lights,

i tossed the LED's that were on it and re-installed new candesant 4" sealed round lights.

 

in the beginning when i bought this truck i didnt notice it had no brake lights, my 360 check was lacking some from excitement and dog tired from driving 150 one way miles in a saturn that would only run 50 mph.

 

i get it home and after several people passing me telling me i only have one brake light, i start diagnosing and checking every wire on it.

the reverse light didnt work nore did the back up signal and the left rear brake light,

so i bought a resistor set for the leds installed one on each side, still no help, next i bought a flasher module

still no help, soi decided to install candasent and still no help, next thing i did was cut the installed harness that had the led resistors.

 

i wired directly over to the lights through the factory connectors , now i have running lights with lights on , no brake lights not even the 3rd brake light, turn signals work, i've checked and replaced all blown fuses .

so just to have brake lights during the day i wired the red wire to the brown wire using the running lights as brake lights.

i have searched every where on the frame for the connector block, apparently mine does not have one.

the harness runs in one big loom from cab to rear of chasis, then splits off to the blue and grey connectors.

i have a tool box bed on it, i can see clearly from one side to the other, even pulled the spare .

 

any ideas how i can get brake lights ?

if i connect the red to green and yellow i have brake lights, but problem is my blinkers act like hazards when in left or right position.

what could be the problem?

I do know the LEDs shorted out and blew fuses, the left side had burned out and the right side was hot , not warm.

why in the world would any one want to ground out their power ?

Led's are Crap and a hazard in my book, your literally ground- shorting your power out on the system just to run low powered bright lights.

 

could I have a bad flasher again?

 

when this is fixed i'll talk about the wihining i'm hearing

 

 

 

 

 

 

 

 

 

[Formulabruce]

1 check power at the connected by the receiver, or at the two connection pins

2. The Brake light switch can cause these issues

3. fuses in side of dash on left and under hood re check.

4. Do a continuity check on each wire from the Brake pedal switch

5. you may have blow a relay under hood

6. Melted wire

7. A "Power probe" and knowledge how to use it, could find the problem fast.

Good luck !

[TBeast2500HD]

I bought a 7 way plug, now I'm waiting on the tow lights to come in, I will check the 7 way on the truck when that arrives.

 

I found the connection block, it has been omitted , they ran a loom from the cab to the rear and split off there,

I have power on the red wire for brakes, for reference sake which wires does it connect to?

if I hook I to the green and yellow I have brake lights with running lights, but when I hit the turn signal both tail lights flash like hazards.

 

that's why I connected it to the brown running lights , I don't drive at night for now, but I have a long trip ahead of me. 2000 mile round trip towing a trailer.

off the harness I have white- ground, green brown-right, yellow brown left, and of course both have white.

I've chased down diagrams and they show red for stop tied in for both sides. does red tie into brown? or the green and yellow?

 

i'll crawl under the cab and chase the loom to the hood and see where it goes soon as I post this.

 

I've even looked at the fuse and relay diagrams, I don't see a relay designated for stop lights.

i'll get some pics and a video today , will be much easier for you to see .

[TBeast2500HD]

1 check power at the connected by the receiver, or at the two connection pins

2. The Brake light switch can cause these issues

3. fuses in side of dash on left and under hood re check.

4. Do a continuity check on each wire from the Brake pedal switch

5. you may have blow a relay under hood

6. Melted wire

7. A "Power probe" and knowledge how to use it, could find the problem fast.

Good luck

I just figured out how to reply. look at my previous post

[Formulabruce]

may need a new flasher in the truck

[TBeast2500HD]

may need a new flasher in the truck

 

actually I changed that first, may have messed it up , I bought 2 . but the question remains, the red brake ties into both the green and the yellow right?

the signal sent through red should work on one while the other flash's if the blinker is on right?

browns running lights only right?

video link below should take you to my dilemma.

 

[Formulabruce]

could be related to the 4 way flasher switch , or brake pedal switch, which is a more common problem.. Those two places are the only ones that tie in the L and R blinker wires, UNless someone wired in one of those adapters for separate trailer lights .

Edit.. Possible turn signal mechanism...

[TBeast2500HD]

could be related to the 4 way flasher switch , or brake pedal switch, which is a more common problem.. Those two places are the only ones that tie in the L and R blinker wires, UNless someone wired in one of those adapters for separate trailer lights .

Edit.. Possible turn signal mechanism...

 

it's got to be the wiring harness,the whole harness has been changed, I found the factory connector box on the frame that's been omitted I've replaced the Led's with candesants, the brake stoplight switch, and the turn signal relay twice. I've got tail,brake and turn signals through the 7way plug on the tow hitch that act the same way.

I've run out of time and money to throw at this beast, so i'm going to wire it back to the running lights just long enough to rent a trailer in the day time, then connect back to the left and right (Green Yellow) and make the haul. just when I make a left or right turn they'll be in hazard mode, but at least they will blink and i'll have bright brake lights at night. my main concern is bright brake lights.

then it's this whining i'm hearing, , I've played with that some, changed the carrier bearing and had the drive shaft balanced. i'm down to thinking its the thrust bearing in the tranny, hard to tell, it whines at certain speeds, accelerate it disappears then re appears, decelerate it disappears. I've changed the rear seals on the axles checked the bearings. I changed the rear out put shaft seal, and now it leaks.

I love this truck but it's driving me crazy