Rear taillight not working

Red Raider · Jan 17, 2022

I have a 2019 FX4. For some reason the passenger side taillight stopped working after I plugged in my trailer. All the trailer lights continue to work. The one light doesn't work even without the trailer being plugged in. I've pulled this same trailer in the past without problems.
I can't find anywhere in the owner's manual where it mentions a dedicated fuse for individual taillights. Any ideas?

Motorcity muscle · Jan 17, 2022

Would check the ground for that taillight

apex96 · Jan 18, 2022

The XLT/FX4 uses an incandescent bulb that functions as the brake and turn signal. I'd first check to see if the bulb has blown or if it has become unseated in the socket.

Red Raider · Jan 18, 2022

I installed LED bulbs when I bought it 2 years ago. I have two trailers that I've used numerous times with no issues. I'd like to know if there is a fuse that might have blown before taking the taillight apart again.

99WhiteC5Coupe · Jan 18, 2022

Red Raider said:
I installed LED bulbs when I bought it 2 years ago. I have two trailers that I've used numerous times with no issues. I'd like to know if there is a fuse that might have blown before taking the taillight apart again.

The LED bulb might be defective.

Red Raider · Jan 18, 2022

That's probably the case. However, it would seem I would be receiving a warning light on the dash if the bulb was out. Just ordered new bulbs

apex96 · Jan 18, 2022

Red Raider said:
I installed LED bulbs when I bought it 2 years ago. I have two trailers that I've used numerous times with no issues. I'd like to know if there is a fuse that might have blown before taking the taillight apart again.

If a fuse had blown, both taillights would not be functioning. Best guess is that particular LED has gone bad. Were the LEDs installed with a load resistor inline to trick the vehicle into thinking you had stock incandescents in there? Have you modified the vehicle code in forscan to stop the vehicle for checking for burnt out bulbs (common to do when switching over to LED)?

duneslider · Jan 19, 2022

I would still consider checking fuses. I had this happen, also directly related to a trailer connection, and it was a fuse and it wasn't apparent to me how they were related but I was told it had something to do with the canbus (or whatever Ford calls it). Anyway, I found a blown fuse and replaced it and all was well.

Red Raider · Jan 20, 2022

Update: It ended up being just the bulb, which I replaced. The things I found confusing: the LED bulbs had been working perfectly for almost 2 years and supposedly should have lasted 100's of hours..........only one stopped working....... The taillights on the trailer worked as they should........ There was no indication on the dash a taillight was out........the fuse configuration in the owners manual didn't show a specific fuse for the taillights. Glad it was a simple fix. Thanks for the help.

Rear taillight not working

Red Raider

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Motorcity muscle

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apex96

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99WhiteC5Coupe

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