Ask TFL: Have You Had Trailer Electronics Problems With The 2021 Ford F-150?

There are a few tricks if you're having this issue

2021 Ford F-150 towing
A TFL reader writes in with some issues towing with their 2021 Ford F-150. (Images: Ford)

Help! I’m having recurring electrical issues with my Ford F-150.

Ilona writes in asking whether we’ve had any specific electrical issues with the 2021 Ford F-150. “I suspect it’s a combination of a brake controller/computer issue”, the email says, and notes there were no former issues towing with a twelfth-generation 2012 F-150.

Here is her initial email in its entirety:

“I’m having reoccurring electrical  issues with my new F-150 with respect to the trailer lights and brakes.  The issues I’m experiencing are as follows:

  • The brakes intermittently work and sometimes stop working completely in the middle of a towing trip.
  • The brake controller in the truck appears to be working inconsistently with both my horse trailer and flat deck trailer.  The brakes activated inconsistently under diagnostic testing, depending on which setting was used.
  • The emergency battery charge pin on the truck doesn’t have any power, therefore the emergency battery doesn’t recharge while I’m driving.
  • There is a low-level power draw on the system, even when the truck is parked.  The rear LED lights on the horse trailer flash continuously when the truck is hitched and turned off with the keys out of the ignition.
  • The ‘Trailer Turn Lamp Fault’ messages come on with no warning in the middle of towing my trailers. 

Have you guys run across these electrical issues with any 2021 F-150s? The dealership was originally trying to blame my trailers, but that’s nonsense, because there was never an issues when I towed them with my 2012 F-150 that I just traded in for my new truck.  I’ve since hauled my horse trailer with friends’ trucks and everything worked just fine. I’d really appreciate any intel that you might have on this. I suspect it’s a combination of a brake controller/computer issue.”

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Some possible solutions if you have this issue

Specifically, we have yet to encounter these specific electrical issues with the new F-150. TFLtruck Managing Editor Andre Smirnov replied to Ilona’s question in another email. In that, he recommended a possible fix if you’re having issues with your 7-pin trailer connector maintaining a solid connection:

“Part of the solution is to put some electric (dielectric) grease on the 7-pin trailer wire connector before plugging it in. Another solution is to use a little bungee cord to pull the cable up and towards the truck when plugged in.  The bungee should ensure the wire is not coming loose while driving.”

However, Ilona responded that following Andre’s suggestion didn’t help.

“Thanks for your advice, Andre. I had already put dielectric grease in the connector plugs on both of my trailers after reading this in online forums. When I had the latest problem on Friday, I removed and replaced the plug several times and had it firmly seated in the connector and still couldn’t get it to work.  I had to drive my loaded hay trailer home with no lights or brakes. Awful. Once I unloaded the hay and went to park the trailer, everything was working again.  It makes no sense at all.  I bought this truck specifically for towing and now I can’t trust it’s safety or reliability.”

Next solution — Warranty repair

Electrical issues can be tricky to nail down, depending on exactly what’s going on. As Ilona pointed out, everything was technically working properly again once she unloaded the trailer. However, Andre has another piece of experience and advice for this issue: “When we had a 2014 Ford Raptor many years ago, our truck’s trailer wiring harness malfunctioned.  We took it to the dealer and it was replaced under warranty.  Your 2021 F-150 may have a faulty trailer wiring module or harness. It’s hard to say.”

It’s worth noting that service technicians should try to replicate the issue, and if they can’t trace it to a faulty harness (or otherwise diagnose the problem), then they may not initially fix it under warranty. If you guys have any similar experiences, please let us know in the comments below and share how you were able to resolve the problem, if you’ve been able to fix it.