Safe to haul with "Trailer brake system fault"?

[tmpkn]

Hey everyone, today my 22 Lariat gave me the "Trailer brake system fault, see manual" error. It started in the morning and came up 100% of the rides throughout the day. It always comes on within 1-15 minutes of starting the engine and will always be triggered by braking. Once I "OK" out of it, it stays quiet until the next engine restart.

Here's the issue: we had road trip holidays planned for the next month starting this weekend. It would be the first time I actually need to haul something, so you can imagine I'm pretty bummed out with the timing. Truck is still under warranty (35k miles), so I called the dealer and they gave me the earliest possible time on Aug 15 (in one freaking month).

I have tried re-seating fuse 91, it didn't help. OBDLink / forscan report no errors.

I have no idea what to do. Is it safe for us to proceed with the road trip or do we need to cancel our Summer plans? Those wait times are no fun

Also - my truck is at 35.4k miles right now. I've got the extended 60k warranty. If I keep driving it for a month, it's gonna be over 36k for sure once my appointment comes up. Will that make any difference?

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[powerboatr]

Got to ask.
Did you check the real grounds on your trailer? Loss of ground is a huge cause of issues...that come and go
Did you try to manually engage trailer brakes to see if it was applying amperage to engage brakes

 

[tmpkn]

The error comes up with no trailer attached, we're due to have the first one ever plugged in this Friday. I'm going to try the fuse 42 and reconnect the "trailer module located above the brake pedal", see if that makes any difference.

 

[powerboatr]

Sorry I was unsure about a trailer
That sort of narrows it down
To the truck
Good luck
I would look at harness connecting module as well. Make sure it's seated
Good luck
When you hook up trailer .you csn test the controller to see if it's sending juice to brakes.

 

[Tone]

Bring it to the dealership. A bad 7/4 plug is a well known issue.

Same happened to my '21. Replaced under warranty. Issue went away.

 

[tmpkn]

Bring it to the dealership. A bad 7/4 plug is a well known issue.

Same happened to my '21. Replaced under warranty. Issue went away.

Do you mean the trailer socket next to the license tag?

 

[Groovicles]

Bring it to the dealership. A bad 7/4 plug is a well known issue.

Same happened to my '21. Replaced under warranty. Issue went away.

You're luckier than me. I have the same fault and dealer says the entire trailer brake module needs to be replace, though of course its on backorder till the end of time. Getting close to 2 months waiting!

 

[Tone]

Do you mean the trailer socket next to the license tag?

Yes.

I would not tow without fixing this. Losing trailer lights is bad, losing brakes is disastrous.

 

[tmpkn]

Yes.

I would not tow without fixing this. Losing trailer lights is bad, losing brakes is disastrous.

Thanks, just to clarify: you had the same issue - this particular error coming up once per drive - and it was caused by a freaking faulty socket?

The day before yesterday I had to haul a big ass sofa from Costco and did ~5 miles with my tailgate open. I wonder if that could have anything to do with it.

Also, I've just ordered a trailer 7/4 plug tester on amazon, will be here tomorrow (unless I can find one today in auto part shops around). Or maybe I can try a multimeter in the meantime.

 

[Tone]

Thanks, just to clarify: you had the same issue - this particular error coming up once per drive - and it was caused by a freaking faulty socket?

It was an occasional error message flash on the dashboard display when driving or starting the vehicle. Dealer Service Manager said these plugs become fouled and fail. They've changed a lot of them.

Doubt the open tailgate was contributory, but it's a 150. Strange things happen.

Good luck. Hopefully the swap will work for you.

 

[tmpkn]

So here's a weird update: I took a can of compressed air and blew inside the 7/4 socket. A bunch of water sprayed out (mostly from the top/7 part), then tried to dry it with a kleenex (not easy because the spacing inside creates like a capillary hold on the water).

Then I drove 3 times for around 30 mins each and so far - no errors.

I wonder if it's possible that there was just enough water there to short the wires when braking (all the water would be squeezed against the back wall of the socket at that point).

Anyway, fingers crossed. If that's not it, I will delete this post lol.

 

[Ford Motor Company]

Hey everyone, today my 22 Lariat gave me the "Trailer brake system fault, see manual" error. It started in the morning and came up 100% of the rides throughout the day. It always comes on within 1-15 minutes of starting the engine and will always be triggered by braking. Once I "OK" out of it, it stays quiet until the next engine restart.

Here's the issue: we had road trip holidays planned for the next month starting this weekend. It would be the first time I actually need to haul something, so you can imagine I'm pretty bummed out with the timing. Truck is still under warranty (35k miles), so I called the dealer and they gave me the earliest possible time on Aug 15 (in one freaking month).

I have tried re-seating fuse 91, it didn't help. OBDLink / forscan report no errors.

I have no idea what to do. Is it safe for us to proceed with the road trip or do we need to cancel our Summer plans? Those wait times are no fun

Also - my truck is at 35.4k miles right now. I've got the extended 60k warranty. If I keep driving it for a month, it's gonna be over 36k for sure once my appointment comes up. Will that make any difference?

Good afternoon, Tom! I would be glad to help you out with this trailer brake fault concern should you need any further assistance. Just shoot us a PM with your VIN and dealer name/location, and I'll get right on it. To send a private message, just click on our username and select "Start Conversation". Thank you!

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