F350 Electrical Problems

[jdarwin]

I'm putting my 2017 F350 in the shop tomorrow but wanted to get some feedback from the group. I have a 2019 3931FB. When I plug into the 7 way in the truck it doesn't seem to charge the battery. Sometimes the truck tells me the trailer is connected and other times it doesn't.

When I get to my destination there's not enough battery juice to run the jacks and slides. I tried running an extension from the truck inverter to the shoreline and it wouldn't run the slides. I checked the out put of both the 7 way and the inverter. The 7 way does have 12VDC to pin 4. However, the inverter is only producing 93VAC. On the battery side, I'm confused why the coach won't charge the battery is there is power. Since I know the inverter is not producing full power, it goes to the shop.

Any ideas on why the coach won't charge?

Thanks

[jetskier]

Originally Posted by jdarwin

I'm putting my 2017 F350 in the shop tomorrow but wanted to get some feedback from the group. I have a 2019 3931FB. When I plug into the 7 way in the truck it doesn't seem to charge the battery. Sometimes the truck tells me the trailer is connected and other times it doesn't.

When I get to my destination there's not enough battery juice to run the jacks and slides. I tried running an extension from the truck inverter to the shoreline and it wouldn't run the slides. I checked the out put of both the 7 way and the inverter. The 7 way does have 12VDC to pin 4. However, the inverter is only producing 93VAC. On the battery side, I'm confused why the coach won't charge the battery is there is power. Since I know the inverter is not producing full power, it goes to the shop.

Any ideas on why the coach won't charge?

Thanks

Squeeze the manual trailer brake lever. Apparently there's an issue with the charge line on 2017+ Superduty trucks until you activate the brakes manually.

[Pops8]

Originally Posted by jetskier

Squeeze the manual trailer brake lever. Apparently there's an issue with the charge line on 2017+ Superduty trucks until you activate the brakes manually.

Is that a one time thing. Or necessary every time you hitch up?

[Slow Hand]

I don't think the truck is the problem. You have to make sure the plug is all the way in the outlet. Check the connection of the trailer wire that goes to the junction box. Mine is on the pin box. Also make sure there is a good ground for the wire on the 5er. A bad ground causes more problems than people realize.

[Theunz]

Don't hold me to this, but I thought that I read some ware that the Fords needed to add a fuse in one of the fuse blocks in order to complete the charging circuit. I might be hallucinating here, but worth googling anyway.

[BB_TX]

I don’t think that was Ford that needed a fuse. I know I didn’t on my 2007 or 2012 F350s. It was already there from new.

[Drifty1]

My thought is Ford doesn’t install the fuse in the panel. Gary Kelly had the problem of not charging and found the fuse missing. Even if you order the towing package it is not installed. This would be the first thing I would check.

[Carl n Susan]

Originally Posted by Drifty1

My thought is Ford doesn’t install the fuse in the panel. Gary Kelly had the problem of not charging and found the fuse missing. Even if you order the towing package it is not installed. This would be the first thing I would check.

As Gary subsequently learned, the 2017's and up no longer use the 12V charge line relay and circuit breaker. Their positions in the fuse panels have no circuitry to connect to. After several trips to the dealer, they finally learned about the new improved system.

All 2017 F-Super Duty vehicles equipped with a factory trailer brake controller (TBC) utilize a trailer module (TRM) which initiates the trailer charging system. For trailer charging to operate, the TRM must detect a trailer is connected and a brake pedal input before charging will be present at the trailer connector. Adding the trailer battery charge relay and fuse into the battery junction box are not required to operate trailer charging with a TRM. This is covered in Ford document SSM 46257.

Ref: https://www.etrailer.com/question-278872.html plus many other internet sources.

[BB_TX]

Thanks Carl. Good to know if I ever trade up.

[jdarwin]

Originally Posted by carl n susan

As Gary subsequently learned, the 2017's and up no longer use the 12V charge line relay and circuit breaker. Their positions in the fuse panels have no circuitry to connect to. After several trips to the dealer, they finally learned about the new improved system.

All 2017 F-Super Duty vehicles equipped with a factory trailer brake controller (TBC) utilize a trailer module (TRM) which initiates the trailer charging system. For trailer charging to operate, the TRM must detect a trailer is connected and a brake pedal input before charging will be present at the trailer connector. Adding the trailer battery charge relay and fuse into the battery junction box are not required to operate trailer charging with a TRM. This is covered in Ford document SSM 46257.

Ref: https://www.etrailer.com/question-278872.html plus many other internet sources.

Thanks for the feedback. I had searched the forum and found the TRM postings. My problem with the 7 way stems from the truck not recognizing the trailer is plugged in. I've tried manually activating the trailer brake and putting it in gear. Sometimes the digital dash reads the trailer is connected and most times it doesn't. I'll check the ground on the truck side of the plug.

Thanks

[SMac]

We had a similar issue, or should I say issues. Long story ended up with our 2017 F350 6.7 L SD and our 2018 3660RL at the Ford dealer. Two issues: (1) the fuse was in place but blown, and (2) they found a small paragraph in a tech bulletin stating that, at times (and I may be paraphrasing) I would have to push the truck brake 3 times in order for the truck to recognize the RV. Seemed strange, but it worked. Haven't had a problem since.

[captl27]

I also have had this problem with my 2010 F350 Diesel. Ontwo occasions the fuse to the 12 volt supply to the trailer plug blew and leftme with low battery by the time I realized it. I carry a spare fuse now andhave installed a digital volt meter on my 5th wheel hitch that I cansee in my mirror. If the fuse goes I can see if the voltage drops in thetrailer.

[Bill M]

Following, own same vehicle SRW

[jetskier]

You may want to install or verify there's a auto reset circuit breaker on the trailer side that would trip before the fuse would blow on the truck. Something in the trailer may be trying to draw a lot of current through the charge line when it's hooked up since it has a higher potential (aka voltage) than the trailer batteries.

[Bill M]

If you have to manually check trailer brakes to activate the charging system this should not be a problem. A manual brake check should always be done as you pull out of your parking spot.

[jeffba]

My 2018 Does not require any braking to detect the trailer to charge it. I can back up to the trailer. Plug in the 7 pin and wahla! I am charging the batteries. For full detection I think there is some braking involved. I do a pull test everytime, so I do not know if it is a manual or foot brake that activates it.

[wed]

If you have tried the above ideas . Your truck will I’d your trailer and all will be fine . If your truck id’s your trailer check you seven way on both the trailer and the truck.

[jdarwin]

I think the problem may be solved. I picked up the coach today. I spoke with the tech who replaced one of the defective cameras on my coach. He told me to turn on my lights and start the engine. Volia! I got voltage to the coach and the truck detected the trailer. I had tried the truck brake and trailer brake switch ideas a couple of weeks ago without success. So I decided to post to this forum. It's interesting that so many folks posted so many different ways to solve this problem. It makes you wonder what the Ford EEs were thinking and that no one from Ford thought to explain this problem.

[DebNJim B]

I have the same tV as OP and have no problem at all. I connect the 7 pin and the trailer is immediately detected. I assume the charging is taking place but I could be wrong as I always test the brakes as soon as I move and before that I have activated the manual lever to lock the brakes to test that my hitch is properly locked. I don't believe the inverter has anything to do with battery charging so the 93v thing is a different situation IMHO. That issue may be because the battery is discharged at that point. If you're measuring 12v at the charging pin of the plug it would seem the problem is in the trailer somewhere.

[captl27]

The brake pin is the 7 pin plug is different then the 12 volt pin that charges the battery the fuses are different. I don't know about newer trucks but my 2010 only signals a failure in the brake circuit not the 12volt charging circuit.