Ppat01

I have a 2014 Ford F150 eco boost and recently found that my rear turn signals and running brake lights do not work. It started a couple months ago, the left one went out and now they’re both out. I’ve replaced the dual filament bulbs and checked all fuses pertaining to the tail end with a multimeter and all seem to be good. I’ve unscrewed, cleaned, and re-tightened all grounds at the tail end. I’ve also installed a new brake light switch. I’ve checked the BCM with a scanner and am getting no codes. I’ve even went as far as cleaning the battery pos and neg connections and touched them for a couple minutes to try and reset the bcm (heard to do this somewhere), but still nothing. Can it be a wire issue? Both tail lights have power and come on when lights are switched on or when car starts, brake and hazards and turn signals just don’t work at the rear end. I’ve heard LEDS can cause problems for these, the previous owner did some re-wiring it looks like and installed mounted cree reverse LED lights. I was desperate so the last thing I tried was cutting the wire to those two mounted cree led reverse lights(was gonna remove them anyways) and still no joy. Could be a BCM problem but there’s no other signs that it could be bad, everything else electronically in the car works perfect. Could it be a different module that’s messed up? Or maybe the turn signal switch? Turn signals blinker indicators also are fast if that helps. Anything helps.

Newbie 5

When you checked the BCM for codes, did you use the Forscan software ? Not all code readers can read the BCM for faults.
Also have you checked your high mount stop light?

Ppat01

I feel like an idiot I just looked at the high mount 3rd brake light and it’s flickering when everything is on. Could that be the problem? Doesn’t the brake light switch go straight to the 3rd brake light first when brake is applied? And no I didn’t use forescan it was a plug in all in one thing I forget the brand. I can try forescan though, will I see more on that?

artsr2002

Not sure how the wiring is but if the light is flickering, yes, it could possibly present a problem. Swap the bulb. As an example, on my 2018 my license plate lights would flicker on when I turned on the lights manually and would immediately turn back off. I could remote start my truck and they would do the same thing, turn on and immediately turn back off. In the end, it was my third brake light. The bulb had burned out. I swapped it out and my license plate lights started working normally again. Another time I got random messages in the IPC. That time, it turned out to be a problem with my front driver side turn signal. I had LED bulbs in there. The bulb had vibrated loose from the socket and fell into the bulb cavity. I fished it out, plugged it back into the socket and put a small dot of super glue on it to keep it in place. No more strange messages on the IPC.

Ppat01

update : I fixed the third brake light and put back in new oem bulbs and it’s working fine. (just the third brake light). I went into the tail light and removed all of the previous wiring that the previous owner put in for leds. He had two load equalizers each on both tail lights, one going to each reverse light and each brake light. I reverse wired his stuff and put all new oem bulbs back into each reverse light socket and brake light socket. Now only the original wires are in. Tail lights have power and turn on when car starts and running lights work, but still no brake lights or turn signals. Could the brake light socket be bad? Maybe the socket for the brake light/turn signal wire is bad and may be the reason why the it has power but won’t activate the second filament for turn signal and brake lights? Anything helps. Also, before I removed the led wiring I bought two led brake lights to see if maybe it would work anyways since it was wired for leds and no still nothing. Everything is back to oem with original wiring.

ProjectSHO89

Go back to the first part of post #2. If the BCM has faulted, the ONLY way to reset it, if it's still capable of that, is with an appropriate scan tool. Nothing else, like disconnecting cables or doing a magic incantation, will reset it.

Details about tools and processes are of critical importance. Don't just gloss over them, especially when specifically asked about them.

The parking lamps are a different circuit from the stop/turn lights although they share a common ground from the bulb sockets.