MSStateDawg

Replaced all 5 related fuses and 4 relays. No joy.
Front turn signals work but they hyper blink.
Brake light on cab works.
Taillights work just not brake lights. Assuming rear bulbs are ok.

Is this a BCM issue? Not a mechanic but I can do most uncomplicated repairs. Something I can do myself or crazy stuff requiring a pro?

Recommend where to buy a BCM if that's the issue?

Thx much.

Newbie 5

I would be removing the rear bulbs and inspect. (two on each side?)
The BCM can shut down a circuit if it senses too much current draw.
You would need to use the Forscan software or something like that to reset the BCM. (or a dealer)
Let us know what you find.

artsr2002

Check the bulbs.

KRUISR

What he said. Some bulbs have two filaments in them. If one breaks, the other still works.

ProjectSHO89

Scan the BCM. If it has faulted, you can check and replace bulbs forever and the new ones still won't work until the BCM has been reset.

Do NOT even think about a new BCM until you know what is going on and diagnostics have determined it has failed. If you do buy one, you'll have a bigger can of worms trying to configure it.

Scarlet

Did you recently replace one or both the rear bulbs? As I recall, the bulb has to be correctly oriented in the socket. Pull one bulb out at a time and try the lights. If the others work, turn the bulb and plug it back in, then try it. If not a bulb issue, pulling one out at a time and trying the lights may give you an indication where the problem is.

mikeru

Why would you assume the rear bulbs are okay? As mentioned already, dual purpose bulbs can have two filaments. One filament for the brake light and one for the running light. Just because the running light works doesn't necessarily mean the turn signal filament hasn't burned out. I don't know which bulbs you have, but it makes sense to start with the simple things and check the bulbs.

D-H

This happened to me last year, taillights would illuminate when locking/unlocking the truck or when turning on parking lights or headlights--but no brake light or turn signal function (3rd brake light still worked).

Got all the typical advice here: check the bulbs, check the fuses, check the ground, check the battery, check the weather at your brother's house, check to see if you have clean underwear on.

It was the BCM. I could reset the fault with forscan which would fix the problem for about 10 minutes.

I brought my truck to a shop that put in a new BCM after a 5-month wait for the backordered part, and they could program it properly.

MSStateDawg

Bulbs were practically new.

Ended up being code P0131 (O2 sensor circuit low voltage) which I cleared and now all's well.

ProjectSHO89

That would have absolutely nothing to do with the stop/turn lights.

Something is missing in this story if "now's all well".