Trailer Brake System Fault (See Manual) After the Recall

[Intellibeam]

So I came home from a 4 day vacation and my Lightning would not remote start. Used the keys to get in and notice the power seat moving super slow. After hitting the power button, I get the trailer error and stop safely now errors. The truck was at 180ish charge. Now it will not drive and won't take a charge. I believe I had the recall on this part done previously as the only one listed for me now is the lighhtbar.

I've never towed and both trailer ports look clean.

Any suggestions?

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[21st Century Truck]

Hmmm... I tow fairly often, in season. Perhaps the truck's trailer brake monitor (the TRM module) has detected unusual signal(s) or unusual behavior from the trailer's brakes? or another component like lights? ...meaning, perhaps there is a safety-related fault but it is on the trailer side, and the truck's towing system is alerting You? Just a guess here from a distance.

 

[Heliian]

Your frunk is open.

 

[Yellow Buddy]

So I came home from a 4 day vacation and my Lightning would not remote start. Used the keys to get in and notice the power seat moving super slow. After hitting the power button, I get the trailer error and stop safely now errors. The truck was at 180ish charge. Now it will not drive and won't take a charge. I believe I had the recall on this part done previously as the only one listed for me now is the lighhtbar.

I've never towed and both trailer ports look clean.

Any suggestions?

The recall was a software update IIRC and dealt with it not actually activating the brakes. I don’t think it gave faults.

Idk if this is useful but I would try a couple of things.
1) Software reset the truck via steering wheel.
2) Pull the 12V or fuse to hard reset the truck.
3) Change trailer profiles to activate one, as well as deactivate one. I would cycle through the profile of electric, hydraulic brakes.
4) If you have an oBD reader I would read the code and/or reset it.

All of those to just get it hopefully going. I would still bring it to the dealer.

Also the error message refers to trailer brake system, I would think it’s the brake controller (inside, pinch levers) I wouldn’t think it’s the trailer pin connectors. If you want to try, the pin connector is really easy to disconnect. Crawler under, locate it and just pinch and pull the connector.

 

[Heliian]

The truck will not remote start with the frunk open.

 

[TaxmanHog]

Extraneous errors might be trigger due to weak 12v battery, is yours the original?

Other members observed your FRUNK open indicator on the instrument panel, is it actually open?

 

[Intellibeam]

Extraneous errors might be trigger due to weak 12v battery, is yours the original?

Other members observed your FRUNK open indicator on the instrument panel, is it actually open?

So here are the steps I tried yesterday and the results.

I thought the battery was original to my 22. So with my odb monitor, it showed 0% state of charge and 9.65v. So I bought that DieHard H3-XEV. While taking my 12v out today, the sticker said 12/23, which was impossible, which means they already swapped it during a recall item. I put the new battery in regardless to test and was 11.5v and 37%. Did the BSM reset as well. Nothing changed.

Frunk was open prior because I was pulling the 2 fuses 91 and 42, they look good. (unless they are both bad? pic attached but I compared them to other fuses and they look similar)

I pulled the trailer coupler connector off the back underside, inspected it and it looks fine.

Attached are various pics. (before and after replacing December 2023 labeled battery.

Trailer brake system fault see manual remains and the truck will not start.

 

[TaxmanHog]

Shop time, for a diagnostic & pin-point test to locate the root cause.
23 amp draw at 11.55 volts, I'm not sure if that's a normal amount of load for a pre-start condition.

 

[Intellibeam]

Shop time, for a diagnostic & pin-point test to locate the root cause.
23 amp draw at 11.55 volts, I'm not sure if that's a normal amount of load for a pre-start condition.

Also when I press the battery button behind the charger door, it spins all red.

I assume this is all covered under the extended warranty plan I got with the truck? I only have 22k miles. How does one get it to the Ford dealer if it won't even start? Is that on me? Thank you.

 

[TaxmanHog]

Also when I press the battery button behind the charger door, it spins all red.

I assume this is all covered under the extended warranty plan I got with the truck? I only have 22k miles. How does one get it to the Ford dealer if it won't even start? Is that on me? Thank you.

Flat bed tow truck.

 

[chriserx]

I'm looking at the negative amps on the LVB Current, is it the formatting of that particular app or does it represent drawing or charging? It made me go look at mine and LVB Current was a positive number.

 

[Intellibeam]

Flat bed tow truck.

Do you know if I am responsible for paying that or is Ford?

 

[chriserx]

Do you know if I am responsible for paying that or is Ford?

Call the dealership, they'll likely arrange pickup, they will then assess warranty status, if covered they pay, if not, expect to pay, but in some cases the dealer will pay it if they perform the work for you, especially so if you purchased the vehicle there.

 

[chl]

All sounds like the 12v battery to me, as others said.
Get it up to 14.2 volts or so and see what happens.

Could be the BMS sensor or the system programming for the LV system was not reset properly or has a fault...there was a recall CSB on them a while ago.

One person had similar issues when the swapped the battery and the reason was the lugs on the new battery were not tightened enough - I know sounds hard to believe but thats what fixed it, tightening them up.

Word of caution about the Lightning LV battery: If it gets too low, the DC-DC charger on the Lightning will put much more than the standard 10.5A recommended for a 35Ah battery on it and that will shorten it's lifespan considerably over time. Keep it on a tickle charger with an AGM mode when not being driven as much as possible to avoid high charging currents.

OF course if all else fails get Ford involved and kiss your money good bye unless there is time on you B to B warranty left. Tacking down electrical issues takes time.

 

[TaxmanHog]

I'm looking at the negative amps on the LVB Current, is it the formatting of that particular app or does it represent drawing or charging? It made me go look at mine and LVB Current was a positive number.

Negative means drawing off battery, Positive means charging battery.

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