rr brake & turn signal dont work

[Guest]

On my 2017 express 3500. It bcm-6, which is fuse location 72.

[carriedi]

this should be what the underhood fuse box should be like

[Freddie]

None of my rear lights work ( brake, tail , signals, and reverse lights ) I checked all fuses and there fine . Where do I go from here?

[carriedi]

If none of the rear lights work (brake, turn and reverse) and all the fuses are good, I would look at the wire harness connection. there should be a connector the goes to all the rear lights in the wire harness. See if it has been cut or unplugged.

[Travis]

So some guys hooked a trailer up to my Chevy 2500 express 2016 model. Since then my driver tail light doesn’t work nor does my trailer running lights. All fuse are good, even took to another shop today and they said they couldn’t figure it out. Any suggestions would be great.

[carriedi]

the tail light fuses are under the drivers seat. LT REAR PARK LAMP FUSE. RT REAR PRK LAMP FUSE. Thay both get power to the fuses from the park lamps relay. If you have power on both fuses but one tail light doesn't come on you have a bad connection the the light that is out or you have a bad/wrong bulb in the tail light. Is the license plate light working? Brown wire is for tail lights. Both sides and license.

I would completely remove the trailer wiring first and then see how everything works. Probably could be a bad wiring job.

[905hvac]

Hey I got a 2019 gmc savana 2500. Both my signals flash rapidly but all my signals headlights etc are fine, could This model have a relay that’s wired to the signals that’s bad or is it all controlled by the bcm? All lights are replaced & are oem and I bought the car like this. Hoping it’s not to do with a bad ground.

[carriedi]

there's no flasher for the turn signal. They use the BCM to pulse the turn signal. As long as everything works, I would just let it flash fast.

The bulbs for your vehicle should be 3157. It is possible that someone replaced them with 3057. I don't know if that would cause the fast flash though. They are slightly different in lighting and power usage but I don't know if that would affect the flash time.

https://rxmechanic.com/3057-vs-3157-bulb/

[Guest]

So my passenger rear blinker and driver side headlight aren't working. Front right blinker has the fast blink.

[Guest]

I got it figured out! It was the bcm-6 fuse for the blinker, and I replaced the headlight because the low beam was burned out. I had recently pulled a trailer with a bad ground. So I'm guessing that was the root of my problems, at least for the blinker...

[carriedi]

the body control module controls your turn/brake signal. there is a green wire that comes down your steering column and goes to the BCM. The BCM then sends the signal to the brake/turn element in the tail light. Check the wiring from the turn switch and then from the BCM. You could also try putting power to the green wire at the tail light and see if there is a good connection through the wires at the tail light socket. It should light up when you put power to the green wire at the tail light. Once you find out where you lost the signal from the switch back let me know.

fuses to check in the underhood fuse box are: BCM3 fuse 26 10A (should be good because other parts of the BCM are working), BCM5 fuse 7 10A, BCM6 fuse 72 10A, (the mega fuse should be good 123A)

the parking/tail lights work fine right? It's only the turn/brake light...

[GUEST]

BCM-6 Thank you!