Added my own Accessory Fuse Box

[DonShockley]

When I purchased my 2015 Transit Connect Wagon, the dealer said it would be no problem to add a couple extra circuits for accessories at one of the fuse boxes. After working my way through several sales and service staff members, the “wiring specialist” finally determined that what I wanted was not possible since the spare fuse slots have no connections on the load side (see F43 at top left in photo below) and Ford won’t supply the parts to add them. So in the end I had to come up with my own solution. And knowing wiring but not cars, my first purchase was the wiring diagram book. I may not know how everything shown in it works, but I can make sure I only tie into something I can see documented and feel confident I understand. Initially I tried the basic auto store inline fuse holders with converted fuse legs as power taps. Although the connections were pretty good quality, strong silver solder and multiple layers of heat shrink, I didn’t like the holders just hanging loose and there were too many potential failure points. So after some searching I found some parts that make for a nice clean, almost bulletproof, wiring harness for accessories.

I’ll apologize in advance for the length of this post up and I'll try to break it up into readable sections with a few photos each. I know I have a tendency to overdo the story telling, but I wanted to share what I learned along the way and why I chose to do it that way in the hopes it helps others with similar projects.

Edited August 14, 2015 by DonShockley

[DonShockley]

The first find that met my needs was the FZ-1 Fuzeblock to act as a convenient wiring point for accessories like my dash cam and phone charger. The big draw for me was the ease of use. Six screw terminals for extra circuit wiring, built in relay for switched power, and making any circuit switched or constant just by moving the fuse for that circuit to the appropriate set of contacts. http://www.amazon.com/gp/product/B00L3OJW4C?psc=1&redirect=true&ref_=od_aui_detailpages00

The second find was the Delphi Metripack 6-Way Female Inline connector that lets you build a waterproof, direct wired (no splices), triple fuse holder that is very similar to the OEM connectors used throughout the vehicle. The only downside is that you need a variety of sizes of numerous small parts to fit assorted wire sizes and most of the smalls had minimum order quantities of 100, so the parts bill climbs quickly. On the plus side, I have enough leftovers to do another 4-5 vehicles the same way mine was done and another 15-20 smaller setups. So if anybody else wants to try something similar and needs the parts, I can hook you up without the extra cost of those stupid minimum quantities. http://www.waytekwire.com/item/38076/Delphi-12059573-Metri-Pack-280-Series-6-Way/

The final find was alongside the 6-Way Connector and provides a nice way to tap power from the supply side of those spare fuse slots. It’s a brass fuse leg with a spade connector on the other end for connecting your wires. http://www.waytekwire.com/item/37065/Mini-Tapper-Fuse-Clip/

I also decided that since I was already spending way too much, I might as well go all the way and upgrade the wire also. Instead of the standard primary wire from the auto store, I went with some more temperature and abrasion resistant wire since it was going to be running under trim. Better safe than sorry. http://www.wirebarn.com/GXL-Automotive-Wire-by-the-Foot_c_29.html

Edited February 11, 2017 by DonShockley

[DonShockley]

The Transit Connect wiring is not very DIY friendly for direct battery wiring, or using either of the engine fuse blocks. And even though the passenger footwell fuse block is closest to where I needed power, it was not very usable for a neat and well protected wiring project. It is also part of the BCM and not being much of a car guy, I took to heart the numerous warnings I was reading from various sources about the potential dangers of trying to tie extra circuits in to the BCM. So that set of fuses was off limits too.

But the fuse block in the cargo compartment is nearly perfect. It is easily accessible, has plenty of spare fuse slots, and is in a large recess with plenty of room to work. And since it already has it’s own Auxiliary Ignition Relay controlled by the BCM, it has both switched and constant power available. So in the end, the best solution was to mount the FZ-1 Fuzeblock up front where power was needed and supply it with a long wire harness running down the right side of the vehicle to connect it to the rear fuse panel.

Edited August 14, 2015 by DonShockley

[DonShockley]

I removed the lower right cargo trim panel to run and mount the wires. And then removed both right sided door sill trims. Everything uses either those friction fit pins that you can just pull loose or plastic rivets where you just pry up the center button then pull out the rivet. Finally, I removed the glove box. This was the only spot that gave me trouble but mostly due to trying to do the work around midnight to beat the Texas heat and not seeing the removable BLACK hinge pins on the bottom of the glove box. If you don’t point the flashlight correctly, it’s amazing what you can miss in the dark even with your nose 3 inches away from the part. But they just pull out, towards the center of the glove box, and then a little twist of the glove box to clear the catches and then it comes out easily.

I decided to mount the FZ-1 to the back of the glove box. Not as easily accessible as inside the box or on the dash itself, but more protection for the wires while still keeping fairly easy access (once you know what you’re doing) by pulling out the glove box. For the ground connection, I used 12ga wire to the ground screw under the middle of the front passenger door sill trim. For the constant and switched power leads, I fed one 12ga and one 18ga wire from the rear cargo fuse block up to the FZ-1 Fuzeblock up front. I was following the routing of the power wire previously installed by the dealer when they installed my Ford accessory trailer hitch as part of the purchase deal.

Here's my Photo Album with photos of the wire routing.

Underneath the right rear trim panel. Also note the Ford trailer wiring controller near the fuse box

Behind the AC duct in front of the wheel well. There were even a couple unused holes that were perfect for the zip tie mounts.

Unfortunately, I didn’t think to start taking photos until I already had the door sill trim pieces reinstalled.

Wires exiting behind removed Glove Box. Also note BCM fuse box on firewall.

FZ-1 Accessory fuse block all wired up

UPDATE: Don't mount anything where I have that small accessory power brick clamped! This morning when I was under the dash investigating a mystery fuse at F61, I noticed that piece was pressed up against one of the wiring harnesses when the glove box was closed. I relocated it and won't be mounting anything to that portion of the glove box any more, the clearances are too tight and I don't want to risk damaging the OEM wiring.

Fuse holder installed on wires at cargo area fuse block

Initial location I tried mounting the fuse holder

Final location where fuse holder was mounted. Better access and appearance

Edited August 20, 2015 by DonShockley

[DonShockley]

There are a couple very minor changes I would make if I were doing it again. I didn’t know exactly how long of wires I would need or where I would mount the extra fuse holder, so I left the wires long enough to reach well out of the panel to make it easier to properly attach the fittings on the wires. A nice neat job can’t have too much extra wire hanging out so I would shorten everything to just enough spare wire for later repairs to the ends if needed. Similarly, instead of running wires to the bottom as I did initially, I would route the wires on top of the cargo area fuse block closer to where I finally ended up mounting the extra fuse holder. And I would prebuild all connections in a comfortable work area for the best crimp jobs and such I can manage.

Oh wait, I’ve got lots of extra parts! So I did exactly that and built a second wire harness. It's just too tempting to start playing around when you have a ton of extras laying around. I also decided to build another version that’s just a break out to add a convenient wiring terminal strip for any future needs. I didn’t want to install it yet since I don’t actually need it but I wanted to see how it would fit so I used the mount/cover I installed for the FZ-1 harness.

I’ve already started thinking about and researching parts for the next upgrade, adding power points up in that nice roomy headliner shelf.

Edited August 14, 2015 by DonShockley

[103west43rd]

Terrific post!!!

[windguy]

thanks for posting. nice job!

[Paul Hauser]

Nice job, (your certainly well fused) and thanks for the great write up.

[buckethead]

Very nicely done. How much power is available at the cargo fuse block? I mean can I run a 2K inverter back there?

[DonShockley]

Very nicely done. How much power is available at the cargo fuse block? I mean can I run a 2K inverter back there?

There is a 70 amp fuse at the High Current Battery Junction Box that feeds back to the Auxiliary Junction Box in the rear. So that would be the absolute maximum. 2KW / 12V = 167A so it would not work. With my work, I made sure to stick within the amp limits of existing but unused circuits. For example: I connected the 30A constant power wire to the 40A circuit at F27 and I connected the 3A trigger power wire to the 10A circuit at F38. And the fuses I used in my work were for the lower values, so there should be no risk of overloading the OEM wiring since I am below what the box was designed to handle.

[buckethead]

I'm embarrassed you had to do the math for me but thank you DonShockley. Not going to work. I need a big inverter in the passenger cargo area so I figured I would have to run a big wire through the firewall somehow. Can I use the frame for ground?

[DonShockley]

I'm new to doing wiring extras on my vehicle so I'm definitely no expert, but frame grounding does seem to be how most auto stuff I've seen so far is done.

[G B L]

If you are running a 2 K inverter you want to run both a positive and a negative Directly from the Battery and you need 2Gage or bigger wire with a fuse at the battery. If the you load the inverter and the engine is not running the battery will last less than 15 minutes.

[rmcinak]

Awesome write-up. 

If starting from scratch without already having your add-on fuse block behind the glove compartment, what routes would you consider for running wires to the overhead shelf area? Through the side up to the front (like you have already done) and then up somehow or up from the cargo fuse box and through the headliner? Or some other magical way? I'm thinking up there would be a good spot to have a stealth switched power point.

[DonShockley]

I did the the USB & Power Point addition to the overhead liner also. The writeup for that project details the routing I used.

USB and Power Point in Overhead Shelf

[rmcinak]

Ahhh, my apologies for not already seeing that.

[Tiller]

Don: Thank you for this post!  I'm in the process of doing this and you're work has helped me greatly.

I did just want to confirm on thing on the F-Z1 Fuse block.  If I'm wiring some thing to the fuse block I don't necessarily have to run a wire from ground side right?  If I have a grounding spot on the frame near what I'm mounting I can use that instead.  Then I only have to wire the hot side from the F-Z1 Fuse block to an on/off switch (if desired) and the hot side of the device.

Like you did I eventually want to send some power from the rear fuse box to the headliner in the front.  But I can ground any devices in the header liner to the closest grounding screw. No need to go all the way back the F-Z1 fuse block.  Right?

Thanks!

Tiller

[DonShockley]

Grounding in the headliner should work fine.