I opened up the dash on my 2012 Ford E-350 cutaway (with a Starcraft Allstar bus body) to replace the factory radio.

In addition to the wire harnesses (and vacuum lines) for the HVAC, 12v plugs, and wheelchair lift controller, I see these three unused wire harnesses (circled):

dash picture

Close-up of the top (red circle):

top harness

Close-up of the bottom (blue circle):

bottom harnesses

The two harnesses at the bottom actually have dead sockets on the back of the trim to hold them and prevent them from rattling around, but there are no electrical connections:

dead sockets

All of these wires are part of the Ford wiring assembly, not part of the systems added later by Starcraft when they assembled the bus.

What are all of these wires for?

  • Look at all the stuff that comes on the more expensive trim levels than you bought - that's what they'll be for.
    – J...
    Dec 24, 2021 at 13:41

1 Answer 1


I found an image of a 2013 E350 dash online, which shows what these might be used for ...

enter image description here

Red Circle:

At least part of these controls appear to be for aux audio input. The two top parts appear to be a 3.5mm input jack, as well as what is next to it is for a USB connection. These would be used in conjunction with the stock radio head unit. Not sure what's going on below it, but some of the images I've seen are to turn the passenger side airbag off.

Green Square:

These are some kind of toggle switches. Most likely, these are for auxiliary lighting.

Blue Arrow:

This is for trailer assisted braking. It's a bias control with which you can turn up the brakes on a trailer to provide more braking force versus how hard you are pressing on the main vehicle's brake pedal.

Again, all of these are going to be used with what comes on the vehicle. If there's nothing attached to the other end, you're not going to be able to put these bits/pieces in place and make something work. It takes the entire system for it to work.

The reason these plugs are present is, it's cheaper for the manufacturer to produce a single wiring harness which is compatible with multiple vehicles (ie: F-150, F-250, F-350, E-150, E-250, & E-350) with multiple options, than it is to engineer/produce a different wiring harness for each one.

  • 1
    Green square: "Upfitter switches," used for customer-installed lighting, winches, or whatever. When selected, they lead to relay-controlled blunt-cut wires under the dash. Bottom half of red circle: Passenger airbag disable, required by law for vehicles with no (child seat compatible) rear seats. The slot is a switch that requires a key to turn, causing the round amber disable light to illuminate.
    – user71659
    Dec 24, 2021 at 19:27

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