How to Connect Brake Controller and 12V Power Wiring Connections for a 1998 Ford E-350

Question:

Mid way thorough my 1998 ford e-350 15 passenger install after picking up the parts here https://www.etrailer.com/question-701673.html. I found the OEM connector under the dash to connect my Curt Custom Wiring Adapter # C51322 , but cannot locate the OEM blue wire at the rear of the vehicle, so Im planning to splice into the blue wire from the Wiring Adapter # C51322 and run it to the blue terminal on the 4-Pole to 7-Pole and 4-Pole # 37185 at rear of vehicle. Is this the right approach? I also see there is a black wire coming off the 4-Pole to 7-Pole and 4-Pole # 37185. I wasnt planning to run another black wire to the rear, and thought the brown wire from the OEM 4pin was my +12V, Do I need to run a separate power wire back to the rear? If so should I splice that off the Wiring Adapter # C51322 or run it directly from the positive battery terminal through a 30A circuit breaker? Lastly, for these splices in the dash, are T-connectors recommended or is there a better way? Thanks

asked by: Erik O

Expert Reply:

Before I get into the wiring itself I do want to make sure you've looked in the correct location for the OEM wiring on your 1998 Ford E-350. Attached is a clip from our linked wiring article so you can see how to gain access to the wiring for your brake controller and 12V power connections.

If you aren't able to find the OEM wiring on your E-350, you will want to connect the blue wire from the Curt Adapter # C51322 to the Blue wire on the Hopkins Connector # 37185.

The brown wire on that Hopkins is for the running light circuit so you will need to also run 10 Gauge wire from the black wire to the positive terminal on your battery (through the 40A Circuit Breaker like part # 9510). You won't want to tie this into any other wiring circuits as that could overload them.

I recommend making all of your 10 Gauge Wire connections with Heat Shrink Butt Connectors # DW05745-10 since they provide the best protection against the elements.