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Topic: Help for my RV Friend [Towed charge line not working] (Read 427 times) previous topic - next topic
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Help for my RV Friend [Towed charge line not working]
[Modified topic title to be more descriptive - Michelle]


I’m unable to help my RV friend with his Class C on a Ford E350 chassis.  I have included his message to me.  Perhaps someone in this neighborhood can help him?  The RV shop that installed his towing system can’t help him. 

*****
I recently purchased a 2020 Thor Chateau 26B on a 2019 Ford E-350 chassis. I'm towing a 2017 Equinox with Blue Ox and the Stay and Play Duo braking system.

The one problem I am having involves the 7 pin connector on the back of the RV. Pin 4 "Aux 12V+ Charging" is not providing the expected 12 volts even with the engine running and transmission in drive. This prevents the line charger from keeping the toad battery charged.

The fuse in the E-350 for this (#17) is present and appears good. The required relay in the fuse box is also present. There's no power in the wire that feeds connector pin 4, so this is not a connector problem. Whatever is wrong must be in front of the 7 pin connector. What could be killing the power to 7 pin connector pin 4? Thanks!
*****
If we receive any help, I’ll immediately pass it on to him.  And thank you.
Re: Help for my RV Friend
Reply #1 –
Dear Ed & Margee's friend,

"The RV shop that installed his towing system can’t help him" doesn't seem to be an acceptable response from the installer.  If I understood your friend's issue correctly, it is a wiring issue.  A four pin connector has one pin for stop lights, one pin for lights, one pin for left turn signal and one pin for right turn signal.  You need a separate wire run for the charging of the toad battery.  Without that charge wire, your toad battery will soon die.  If the installer refuses or cannot figure it out, then your friend should go to any knowledgeable trailer/towing dealer for a diagnosis and fix.

Best,

Gary & Karen and the Doodles......
2007 30' TB
Re: Help for my RV Friend
Reply #2 –
Ed-

I assume the E-350 is on a 2019 chassis, with a V-10 engine. Things may be different for a V-8-equipped chassis.

Trailer wiring diagram for the 2019 E-series is at Ford Body Builder Advisory Service - Publications (link here). Scroll to "Body Builder Layout Book," then Press the "Show More" button, then select the "2019 BBLB-E-SERIES." Look at page 32. I'm sorry I can't provide a direct link, as it appears Ford doesn't allow that with my browser.

Online owner's manual for a 2019 Ford E-350 is at this link.

Looking at the diagram in the Body Builder Layout Book, fuse #17 in the fuse box under the hood supplies 12V to more than just the trailer tow battery charge.

I suggest he replace the 30A fuse in position 63 of the fuse box under the hood. He could swap with fuse #18, as a test.

Also, relay #4 in that box is the trailer tow battery charge relay. He could try swapping relay #4 and relay #6, as a test.

Mark H.
Former owner, 31-foot gas Class A
Former owner, 1997-8 mid-bath
Re: Help for my RV Friend
Reply #3 –
Hi Ed or Margee;  The Thor Chateau 2019 Ford e350 does come standard with a 7 pin bumper connector.  https://static.nhtsa.gov/odi/tsbs/2019/MC-10160542-9999.pdf   Any RV repair place should be able to verify the presence of +12 VDC at that pin #4.  So first you need to know if that Fuse #17 has power (+12v) present at it's input. Even if the fuse is good, doesn't mean that there isn't another distribution fuse in front of it (electrically) that could be bad.  Second, if there is power on both sides of fuse #17, the relay has to operate in order for the power to get to the bumper 7 pin socket. I assume this relay operates to prevent a power drain to the towed vehicle, while the motorhome engine isn't running.
   The towed vehicle may still end up with a dead battery, even if there is 12v. at pin 4 of the 7 pin socket.  Are you sure that there is no voltage at pin 4?  It takes more than 12v to charge a 12v. battery.  Usually the towing motorhome with engine running will have about 13.6 volts present at that pin.  Often a dc/dc booster can "suck" more current out of that pin and boost it to a higher voltage to better keep the towed vehicle's battery fully charged.
    The question I should have asked first is: has this setup ever worked? If it did, did it suddenly quit working?  Are the connecting cables clean and tight?  Somewhere on the motorhome (if I remember correctly) there is a connector underneath near a frame rail, a few feet in front  of the bumper that could have become unplugged.   Are all of the other signals on that rear bumper socket working correctly at this time?
    The Auxiliary 12V going to that socket could have be accidentally shorted, just a momentary contact, and blown a fuse under the hood in the main power distribution box. Driver side under the hood.  I don't have a wiring diagram for that new a chassis. A Ford dealer, really any mechanic, should be able to help with that.  RonB
     Thanks Mark, beat me to that.
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Help for my RV Friend
Reply #4 –
On behalf of my amigo, thank you 🙏 so much.  The above guidance should go a long ways to helping him.  He’ll work tirelessly to fix this himself.   Once he has this issue sorted, I’ll post the results. 

Btw, he and his wife wanted a newer LD and looked for good while before buying this one. 
Re: Help for my RV Friend
Reply #5 –
On some newer Chevrolet with towing package, the number 4 wire is present but not hooked up. It's taped to the harness in the area of the fuse box. I think after you hook it up you will also have to install a 30 amp fuse. Bear in mind this is on a 2500 Chevy pickup, Ford might be similar. You tube might be your friend.


Jon.
1994 MB
Re: Help for my RV Friend
Reply #6 –
As an aside,  We tow a 1998 Jeep behind our 2001 LD. We put a Harbor Freight solar panel https://www.harborfreight.com/15-watt-solar-battery-maintainer-64251.html  on the Jeeps dash.  It helps to keep the battery charged while we tow.  Plugged into the cigatette 12v outlet it backfeeds the battery.  It has done a great job, including getting us home one day when the alternator quit working and we needed a little boost to restart.
Sand Castle (Theresa & Everett) Surfside
01'  26.5 Mid Bath,   2018 31IB
Michigan born and starting to explore the US with my  spouse and our furry friend. Enjoying joining LD group rallies.
Re: Help for my RV Friend
Reply #7 –
That's a quick, easy, and cheap solution that's worth considering.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Help for my RV Friend
Reply #8 –
As a follow up.   And allow me to add my appreciation for the help. 

Quote
Ed - please extend my deepest thanks to whoever provided this response. They clearly know their stuff. The wiring diagrams in the Body Builders are very helpful.

The problem was fuse # 63.  The fuse we checked, # 17, is upstream of the fuse that was bad. In my case, fuse 17 was a decoy. I probably wouldn’t have discovered 63 without help.

Since the toad is newly converted, I plan to take it for a test tow to see if fuse 63 blows again.

Thanks Ed, and thanks to whomever provided that very useful information.
Re: Help for my RV Friend
Reply #9 –
Thanks for the solar charger link, TLBB20. It could be very helpful for our 2019 Subaru Outback with ever draining battery problems. I wonder if there would be a risk of overcharging it.
Susan Wilson
'95 MB
'03  Front Lounge
'15   TK
‘21 MB
 
Re: Help for my RV Friend
Reply #10 –
Haven't had any trouble, it was created as a battery maintainer.
Sand Castle (Theresa & Everett) Surfside
01'  26.5 Mid Bath,   2018 31IB
Michigan born and starting to explore the US with my  spouse and our furry friend. Enjoying joining LD group rallies.