Trailer Brake wiring location? - 07.5 3500 DRW

[Rogan]

So yesterday, I finally started tackling installing the Mopar "add-on" trailer (7-pin) kit.   The reasoning is the PO had some kinda hack-job of a setup..  A busted 7 pin connector, and a piece of 14/2 wire (only using one) ran from the 7 way at bumper, up the driver's side rail, to the plug behind the LF wheel-well.  Tapped into a green wire.

This is apparently a 12VConstant (green) fed to the brake terminal of the 7-way.  WTAF??

So at any rate, the MOPAR replacement with harness is in, minus the blue brake wire..
The new harness has a blue pigtail that is apparently to go to the under-dash somewhere. 
There's already a trailer brake in the cab, plugged in to the junction block above the clutch pedal.
Shouldn't I have access to this wire somewhere underneath the truck?

The replacement plug in the bumper connects to the harness by 2 plugs:  one plugs into the actual 7-way, and another plugs into the 4-pin OE connector above the class 3 hitch mounting (again, factory).   But there's no trailer brake wiring/connector anywhere I can see, at the back.

The plug under the LF wheel-well liner, I cannot figure out what connector it is, or its pin-out, by looking at the 08 FSM..   Any help is greatly appreciated.

 

 

Rick

[Rogan]

OK, I'll post pics later (they're on my phone)..  But I found the trailer brake wire (it's the one I thought it was, at this plug)..Dk Green.  it's sitting at 12VDC all the time.  Cut the Lt Blue wire out of the brake controller, and it dropped to 0V at the green wire, but still 12V out on the controller..  Bad/failed controller, apparently.  lol

 

 

[AH64ID]

What kind of controller? Maybe it’s looking for resistance to check brakes and will drop the voltage once it senses a trailer. 

[Rogan]

DrawTite Activator IV.  I read this last night:
If you detect constant 12V power on the blue output wire when the brake is not pressed, then the controller is damaged and must be replaced. If the controller passes these tests, then the problem could be in your connectors or trailer wiring.

 

 

I ordered a Curt for a replacement.

 

Edited August 9, 2021 by Rogan

[Rogan]

I said Curt..  Meant Hopkins.  lol 

Edited August 12, 2021 by Mopar1973Man