2018 Mustang passenger side lights don't come on, blinkers work though

[squat01]

The rear passenger side taillight does not come on when the rest of the lights do at night. The blinker for that side works fine though.

The same issue is happening with the amber light up front on the passenger side. Again, the blinker lights up just fine.

I assume this is a fuse issue but haven't found one that's blown. Is there a hidden fuse box I don't know about

Edit: I forgot to say it's the 4 cylinder

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[spedy7]

I had a similar issue about a month ago, my dad noticed my rear running light on the driver side was out. DTC was set for the driver front parking light circuit. Looking at the wiring diagrams, both run off the same FET enable circuit from the BCM (the rear signal lights run off the BCM-B). I'd guess a random BCM fault, poor pin fitment within the connector, or a random overload/short on one of the circuits triggering FET protection. In my case, it resolved itself for now, seems like lights on the S550 can get a bit finicky.

 

[squat01]

Thanks for the reply. I actually just got back from the dealer service center where it seems to have fixed itself.

I tried to show him the issue and to do so I had to turn the headlamp from auto to 'on' and they all came on. I tried for a few minutes to see if I could get the passenger side to go off and they just worked. I wonder if simply flipping the dial from auto to on fixed my issue for now.

 

[HiTekExec]

I had a similar issue about a month ago, my dad noticed my rear running light on the driver side was out. DTC was set for the driver front parking light circuit. Looking at the wiring diagrams, both run off the same FET enable circuit from the BCM (the rear signal lights run off the BCM-B). I'd guess a random BCM fault, poor pin fitment within the connector, or a random overload/short on one of the circuits triggering FET protection. In my case, it resolved itself for now, seems like lights on the S550 can get a bit finicky.

Very interesting... just had my passenger rear not lighting...zip nada nothing on running, blinker or brake...until I accidentally hit the wiper switch! then all came back even with the wiper off. Oh yeah, I had to see that again. Restarted the car, no lights, hit the wipers and the lights are back; nice having a repeatable fault and workaround condition at least for troubleshooting. Haven't tried other switches for their effect yet, and I need to look at the wiring diagram for a '21 GT500, but sure seems like a funky ground at some pin somewhere.

 

[Crossi]

Have a similar issue. Mine is with the front passenger though. Amber blinkers work fine but the white driving light doesn't work anymore. Anyone find an actual fix other than pesky gremlins?

 

[HiTekExec]

Do you have your lights on “auto”?
Mine were and while troubleshooting I rotated through that switch several times, and have not been able to duplicate the anomaly since.

 

[mejohn50]

I wonder if simply flipping the dial from auto to on fixed my issue for now.

When I picked up my 2019 the same thing happened except it was driver’s side. Headlights and tail lights on that side didn’t work for some reason, but brakes and turn signals did. Turned the lights from auto to off, turned them back on, and it’s been fine for three and a half years.

https://www.mustang6g.com/forums/threads/2019-gt-tail-lamp-front-marker-lamp-out.111445/

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