7 Pin Trailer Harness / Dual Batt Option

[bkgc5]

I have 2004 3500 with factory dual batt, dual alt, I just purchased a trailer that needs the 12 volt pwr in the harness. I have tested the harness and it has no 12 volt power and I have checked the fuze post 2 to ensure the fuse was not blown or bad . As I read thru the owners manual it states that post one is NOT used due to the dual batt option but I have a feeling that the fuze needs to be there to supply pwr to that harness .

 

why is this post Not used and hoe do I get pwr to that factory 12 trailer plug ????

[neonhomer]

I dont think it is the one on the left, it is the one on the right... That is where my trailer harness fuse is.... top row right.

 

I have a 450w power inverter wired to post #1 on my truck.. but I don't have the dual batt option, but I do have the tray....

[bill190]

Yes, it is correct that the fuse to Stud 1 should not be there with a dual battery. This keeps the two batteries separated which you want.

 

Then coming off of the auxilliary battery (down the line) is a wire going to "Trailer connector E"

 

For the life of me, I can't find "Trailer connector E" or what that goes to???? (On the wiring diagram)

 

Anyone know?

[bkgc5]

Yes, it is correct that the fuse to Stud 1 should not be there with a dual battery. This keeps the two batteries separated which you want.

 

Then coming off of the auxilliary battery (down the line) is a wire going to "Trailer connector E"

 

For the life of me, I can't find "Trailer connector E" or what that goes to???? (On the wiring diagram)

 

Anyone know?

 

 

So what does the second batt do???? or how do you tap into the second batt ?

[mfennema]

It looks to me like trailer connector E is the positive battery voltage based on the attached schematic. trailer_schematic.pdf

trailer_schematic.pdf

trailer_schematic.pdf

trailer_schematic.pdf

[bill190]

I found "Trailer E"

 

There is a connector for the trailer wiring under the rear bumper in the center.

 

On this connector would be a red wire coming from the front of the vehicle. That red wire should be +12 volts from the Auxilliary battery.

 

Perhaps this red wire was not passed through to the trailer connector on the bumper?