Ford Transit USA Forum banner

Auxiliary wiring and fuses

17077 Views 4 Replies 3 Participants Last post by  asdrew
I'm trying to get a handle on how to wire aux devices, such as a 12v socket and digital voltmeter, but the BEMM guide is quite confusing to me. It says to never connect anything to the battery, but rather only to the customer connection points. But I think there are more spare fuses than customer connection points, aren't there? Am I supposed to wire directly into the fuse box?
1 - 2 of 5 Posts
As jonsobi said, there are many ways to wire in extra outlets. This is what I did when adding extra electrical connection points all over my wagon, connected in a variety of ways.

I decided for the most part that I wanted them controlled by the 30 minute circuit which activates when a door is opened or the ignition is on and shuts off 30 minutes after one of those events ends. The three 12v factory plugs use this 60A circuit, fused at 20A each.

1. In the dash, I popped the tray up where the lower factory 12v plug is and tapped off both + and - wires (both seem to be switched in different ways). From that I added a dual USB plug where the unused USB hole next to the aux audio jack is. This is now the most used port in the vehicle.

2. Down the passenger side, I tapped off the wires for the 12v plug just behind the door and did the same thing for another dual USB plug near it in the face of the horizontal trim piece which pops off. I also extended wires from there to the rear on that side and added a 12v + dual USB + voltmeter port by the back door.

3. Down the driver side, I wanted power for the passengers too, and for that location I used the 60A customer connection point at the base of the driver's seat. I made up a panel triggered by a relay which energizes from a + wire run back from the 12v point I tapped into at the center console. Since on occasion I may want to leave something powered without the 30 min circuit, I added a lighted SPST switch which energizes another relay to power the circuit direct. This powers a fuse block I added to distribute to one more 12v + dual USB + voltmeter port and Two 400W inverters, one in the front and one at the rear door.

I don't expect to draw significant power from any of these points for any length of time and now you are never more than a few feet away from a variety of power sources :D
See less See more
There are at least three different 20A circuits (F47, 48, 49) pulled from the 60A 30-minute circuit (F44), one for each of the three 12v factory plugs.

The lower one in front now shares with a double USB port and also triggers the low draw relay for the aux power behind the driver down the side.

The one behind the sliding door now shares with two double USB ports and an extra 12v plug as well as the voltmeter.

The panel I made up behind the driver for that side draws power from the 60A CCP.

There will only be one or two items plugged into any of the circuits at a given time, so the main purpose is to offer more places to plug things in safely.

I assume the BEMM guide wants all wiring to be separate from the factory system for various safety purposes, and also that some circuits are monitored for load by the BCM. Gone are the days when we could randomly pull power from any live wire we could find - they are all interconnected and controlled by components of the BCM.


See less See more
1 - 2 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.