Fuse / Relays for RV battery charging while towing

[WillF]

Hi All,
New to the forum and just upgraded from an F-150 to a Ram 2500 6.4L mainly for bumper towing a travel trailer. My RV batteries kept going dead on trips with the old F-150 until I discovered the relay that protects that circuit was not present in the power distribution box; I was then able to install it and fix the problem.

I'd like to make sure the charging function is working correctly before taking off, however I do not see a fuse or relay listed in the RAM owner's manual specific to pin 5 (battery) on the 7-pin connector. Can't seem to find any info online. Does anyone happen to know which one it is? Thanks, Will

 

[CharlieL]

Hello Will! Welcome aboard - Good question. From looking at the owners manual, by process of elimination I would guess fuse F30 - 30 amp pink for "TRLR Tow." The owners manual & standard pin connectors appear to be:
F28 = Trailer Tow B/U (backup lights) - Connector Pin 7.
F29 = Trailer Tow Park (parking lights) - Connector Pin 3 - running lights.
F53 = Trailer Tow Left Turn/Stop - Connector Pin 5.
F81 = Trailer Tow Right Turn/Stop - Connector Pin 6.
Ground is Connector Pin 1.
Trailer Brakes is Connector Pin 2. I don't see a fuse listed in owners manual for this.

The standard 7-pin connector shows Pin 4 as "Aux 12v+Charging." My guess is that F30 would run to Pin 4.

 

[WillF]

Hi Charlie,
Thanks so much for the detailed reply. Interestingly, the 7-pin connectors you listed are completely different than those shown in my manual. Here's what I have:

Pin 1 = Backup Lamps
Pin 2 = Running lamps
Pin 3 = Left Stop / turn
Pin 4 = Ground
Pin 5 = Battery
Pin 6 = Right turn / stop
Pin 7 = Electric brakes

That said, the fuses in my manual do match up with what you sent, and I'm agreeing with your guess that F30 is the one, so I'll check that one first.
Thanks again for the help!

 

[CharlieL]

Hi Charlie,
Thanks so much for the detailed reply. Interestingly, the 7-pin connectors you listed are completely different than those shown in my manual. Here's what I have:

Pin 1 = Backup Lamps
Pin 2 = Running lamps
Pin 3 = Left Stop / turn
Pin 4 = Ground
Pin 5 = Battery
Pin 6 = Right turn / stop
Pin 7 = Electric brakes

That said, the fuses in my manual do match up with what you sent, and I'm agreeing with your guess that F30 is the one, so I'll check that one first.
Thanks again for the help!

You are welcome. I just used a common 7-pin connector diagram from on-line for illustration. In retrospect it would have been much smarter to have looked for the pin connector info in the owners manual!

 

[H3LZSN1P3R]

They are powered from the factory unlike some 1/2 tons to confirm check the 12V pin on the 7pin truck side connection would be top right pin

Edit* i forgot our plugs are upside down so bottom left pin when you look under cover

 

[WillF]

You are welcome. I just used a common 7-pin connector diagram from on-line for illustration. In retrospect it would have been much smarter to have looked for the pin connector info in the owners manual!

No worries, Charlie

 

[WillF]

They are powered from the factory unlike some 1/2 tons to confirm check the 12V pin on the 7pin truck side connection would be top right pin

Edit* i forgot our plugs are upside down so bottom left pin when you look under cover

Thanks, I will do that to confirm if it's powered up