Ford Transit Upfitter Switches

When ordering a custom Ford Transit you can add Upfitter Switches, also called auxiliary or accessory switches. These switches allow you to control accessory items like lights, winches, or inverters with factory looking switches.

The switches are simple on/off style with an indicator light located in the center console between the driver and passenger seats. If the key is in the ignition or run position and the switches are turned on (flipped up), they provide a 12 V and 20 A max output.

Upfitter Switches

Four (4) user defined switches can be added to a custom ordered Ford Transit

To order the switches you need to add code 67C to the order:

User-Defined Upfitter Switches (4). Requires Heavy-Duty Alternator (63C) and Dual Heavy-Duty Batteries (63E). Includes Modified Vehicle Wiring System (53K), Customer Connection Point and Auxiliary Fuse Box (87E)

BEMM Diagram

Switch diagram from the Body and Equipment Mounting Manual (BEMM).

To connect anything to the switches you can find their output on connector C33-H under the driver’s seat.

Switch Output Connector

The Switch Output C33-H connector (#4 in the picture above) is located under the driver’s seat on the right side of the pedestal.

Unfortunately Ford made accessing this connector very difficult. It requires removing the driver’s seat (4 T-40 Torx bolts), removing the battery box lid, and then a frustrating amount of time trying to fish out the connector. The connector isn’t just sitting deep in a crevice, it’s attached to one of the wire bundles with electrical tape.

We used a hobby knife to reach down and carefully cut the electrical tape. We then used 2 very long flat head screw drivers to wiggle the connector free and out from under all the stiff wire bundles. This is a practice in patience, don’t attempt this if you’re in a rush.

Location of switch output connector

The connector for the switches is buried under the driver’s seat.

C33-H Switch Output Connector

C33-H connector.

Once you have retrieved the C33-H connector you can plug in the pigtail EU2Z-14S411-XA so that you can easily connect accessories to the switches. The plug has bare wires so you can connect anything you want to them, we added quick disconnects for now.

EU2Z-14S411-XA Connector

EU2Z-14S411-XA connector with added quick disconnects.

We plan on using one of the switches to control the house battery charger and the others might control exterior lights, we’re not sure yet.



  1. Reply
    david hilling November 30, 2016

    Thanks for the tidbit. I hate having to ask on the forum as I will most likely be reminded that the info is already there somewhere. I have my van sans the ordering process, do I have that buried pigtail and if not what is your sense of the process in getting a multi conductor between the toggles and the drivers seat? I get the impression from you that those wires are carrying the loads so the indicator LEDs are sunk to a common ground return. Does each switch have its own feed wire in the bundle? I would probably have a load controlling mini PLC in back as I love to play with them. Hope you enjoyed your trip wow.

    • Reply
      Matt December 18, 2016

      Not sure what you’re asking but let me try to answer. Each switch has 1 wire available at the C33-H connector. Each of these connections are rated at 20 amps. The 4 wires in the C33-H connector are not direct wires back to the switches. The wires go to fuses and relays before they make it to the actual switches.

      • Reply
        David December 19, 2016

        I have been reading the threads not really finding anyone using the upfitter switches as an aftermarket addition. So you never really handled the dash portion of the upfitter switches you just accessed the connector under the seat. Your an EE right? If the physical upfitter switches are passive and only operate relays then I am imagining just six wire leads, 12v, ground and four leads coming off the contact points, with the LED’s simply grounded off the load side of each switch w appropriate voltage drop ballast?

        I haven’t dived into this as deep as I should yet. I have glanced at the upfitter manual but maybe I just need to buy the dash switches portion and figure it out with a power supply and multimeter. I would like to utilize them and keep the stock look.

      • Reply
        david hilling December 19, 2016

        Matt, sorry one more thing. It just occurred to me that those upfitter switches probably illuminate for position/location at night, do they, and just get brighter when in the on position? That would mean another conductor in the harness for (headlights/marker lights) mode?

  2. Reply
    Carleton Lane December 29, 2016

    Thanks for the tidbit on this, I’ve been wondering how these things worked. So for external lights, are you supposed to run a wire back out of that harness and through the firewall? I’ve been trying to interpret all of that stuff in the BEMM manual.

    You guys are the only folks I’ve found that are blogging about pretty much our exact build (ordering today!). 4×4, High Roof, LWB (not extended) & sleeping perpendicular.

    • Reply
      Matt January 2, 2017

      Yes, you would need to run a wire back out to the exterior of the van. And if the external lights you plan on using need more than 20amps you would need to add a relay and power them some other way.

  3. Reply
    Terri December 30, 2016

    Hi Matt, how did you decide to recharge your lithium house batteries from the vehicle? Are you using a Sterling B2B smart charger? An Orton-style solution with vehicle powered inverter and a 2nd inverter/smart charger?

    • Reply
      Matt January 2, 2017

      We are using a second vehicle powered inverter (1000 watt) that only comes on when the engine is running and the first aux switch is on. The vehicle powered inverter then powers our 2000 watt Magnum inverter/charger which charges the 400AmpHrs lithium battery bank.

  4. Reply
    Otto January 23, 2017

    Thought I would mention that on the 2017 Transit the connector for the output on the upfitter switches is no longer under the drivers seat. After pulling the seat & Batteries I searched for the connector, finding only one connector that did not match the one supplied with the modified wiring. I did more digging and found they moved it to behind the glove box, it’s still not easy to get to. You can remove the panel next to the glove box , just pull it out using the finger hole.

    That’s were the other connection is for the upfitter wiring. It has a million wires with no instructions doubt I’ll need to use that one. They supplied a 30 amp fuse but no mention of were to put it.

  5. Reply
    Davey June 19, 2017

    Bought off the lot, but I would have ordered these switchs. The two left switchs use relatively simple harnesses and I plan a power point and buss bar to add circuits when needed. Will still use house and solar systems for extended stays. The right two switches use a harness well beyond my ability to imagine the possibilities, and yet I feel compelled to make every switch do something. RPG for clearing traffic? Or maybe deploy helicopter blades to gain elevation!

  6. Reply
    Fred McCarter July 31, 2017

    MATT, Any luck with a new 2017 Transit? They moved the C33-H connector behind the glove box.
    The BEMM manual says C33-H has outputs positive and ground for upfitter switches 3,4
    The manual is incorrect.
    On C33-H I have 2 always HOT positive and 2 negative – Nothing operated by the switches.
    Even the FORD FIELD ENGINEER has been unable to tell me the new outputs.
    Do you know where I find the four outputs controlled by the switchs?

    • Reply
      Matt July 31, 2017

      It’s behind the glove box on 2017s. Take a look at Otto’s comment on this post.

      • Reply
        Fred McCarter July 31, 2017

        Yes, I know where the C33-H is located. The problem is in the REVISED BEMM Revised 05-2017, the information is incorrect.
        The documentation shows upfitter switch 3 and switch 4 HOT wires are located in the C33-H. The two positive wires coming off the C33-H are HOT whether the switch is on or off.

        • Reply
          Matt July 31, 2017

          Gotcha, yeah I’m not sure. I would ask on the Transit forum.

          • Fred McCarter July 31, 2017

            Thank you for the reply. Yes, I have a FORD Field Service Engineer looking at the problem and even he is confused about where they put the outputs. I think they moved all outputs for the switches to the 42 pin connector behind the glove box. But I don’t want to strip and test 42 different wires. I was hoping they would have released another service bulletin by now.

    • Reply
      Eric February 18, 2018

      Does anyone know where the connector is located on the 2016 Transit. Also is the it the same pigtail in both locations?



      • Reply
        Matt February 18, 2018

        On the 2016 Transit the connection is under the drivers seat. See the pictures in this blog post.

  7. Reply
    Fred McCarter July 31, 2017

    It appears that even Otto is having the problem.
    Thanks for the input. I guess I am still waiting on UPDATED documentation from FORD in the form of a Service Bulletin.
    Bulletin Q-250 tells the new location of C33-H connector. That documentation is also incorrect.

  8. Reply
    Otto July 31, 2017

    I haven’t had a problem with the switches since I haven’t used them. I did plug the harness for the switches with the four wires into the connector behind the dash, right of the glove box. I didn’t plug the other multi wire harness in since I have no need for those circuits. I just assumed the 4 wire connector was for the Aux, switches and did not test them.
    Could be I was wrong and there not for the switches. It would have been nice if Ford provided info with the wiring kit.

    Have my conversion completed and just finished a 900 mile trip, averaged 20 mpg with onboard computer and by actual gallons used, both within a few tenths. 150, 3.5, w/3.31 rear, med roof 130 wb.

    So far I’m very impressed with my Transit.
    Palmer ,Alaska

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