My goal in this project was to come up with a way to aid in the addition of interior accessories (gauges, switches, chargers etc..) to my 2001 super duty while retaining a very clean and factory feel. I believe I have come up with a way to do this with relative ease. This should work with all super duties from 99-07 as the dash substructure is virtually the same.

The factory only gives one or two (I think) customer accessory fuses in the fuse box under the steering wheel. That might work for some. I wanted more with the ability to grow in the future. After reviewing several threads and pictures on retrofitting up-fitter switches into older 7.3 super duties I thought it might be cool to try and utilize the space above the glove box (tons of real estate there) and install an auxiliary fuse block of my own. This space is where ford installed the up-fitter relay box/harness in the 05-07 super duties.

Here is a picture I grabbed off google of the up-fitter relay box installed in a 05-07 truck.




To get started I went ahead and purchased the ford relay box (5C3Z-14A303-AA) as seen in the above photo so that I could use the factory bracket that comes mounted to the box. I tried to find the bracket separately but unfortunately I could not. I'm not going to discard the up-fitter relay box as I am already brainstorming on ways to use it.

Now its time to actually start doing some physical work. Start by removing the glove box. You will need all the space you can get.




In this next photo I show the space that our new fuse block will be taking up as well as a hole that must be drilled into the dash frame to securely mount our new bracket. The bracket is held by two screws on each end. There is a hole in the dash already for the end closest to the driver. We must drill the hole closest to the passenger. No biggie. Real easy.



Here is the fuse block I chose to use. It gives 12 circuits total. 6 will be wired constant hot on a breaker. While the other 6 will be wired with key on switched power. This block also provides a grounding bar too.



Here I show the fuse block attached to the bracket along with the necessary hardware to mount the fuse block to the bracket and the bracket up into the trucks dash. The bracket secures to the dash via two #10-32 screws. I used some large fender washer as well.


Now I'll show a few pictures of the fuse box installed.








Now that the interior fuse block is installed its time to move out to the engine bay and begin mounting the necessary items to supply power to our fuse block. I am going to have 6 circuits constantly hot but running through a breaker so that I can kill those 6 circuits if need be. The other 6 circuits will be hot only when the key is in the run position. I decided to use my old oem GPR as the solenoid/relay to power my 6 switched circuits. I figured that if the GPR could handle the amp draw of 8 glow plugs then it could probably handle whatever I throw at via my 6 circuits.

First thing I did was mount the GPR. I found a perfect spot right next to the starter relay on the passenger side inner fender. Its like it was made for it. I was even able to utilize some ford factory mounting hardware to secure it to the fender. In the last picture I show of the GPR mounted to the fender you can see that I had to use a self tapper on the very bottom of the GPR to secure it.









Now to mount the circuit breaker. I used two self tappers to secure it to the fender. It fits in between the fender and battery. With the battery installed, there is just enough room to get your hand in between the two to manipulate the breaker.





One more item to mount and that's the exterior fuse block. There is a flat section just above the passenger headlight on the radiator support(??) that is perfect for this.




The last thing to do before wiring is to identify the grommet that we will use to get our wire from the interior block out to the exterior block. Here is the grommet we will use.







Now its time to start wiring. I went overkill on this. I used 8ga wire for my install. I got on amazon and purchased 8ga wire, all the necessary ring terminals/lugs that I was going to need to make all my connections. I even bought some marine grade heatshrink and crimper tool for this job. Really impressed with this crimper.



Here I show some pictures of a crimp and then a cable in its finished form.






As I started routing my wires through the grommet I showed above I found it increasingly difficult to get my hand between the firewall and inner splash shield. So, I did something I really didn't want to do and that was to remove the inner splash shield. First time I had ever done it . It really wasn't that difficult. Took all of ten minuets and it was out. FYI it helps to remove the wheel when you go to reinstall the splash shield.



Here is what the wires looked like all secured and rtv'd before I reinstalled the wheel well liner.




Here's what the wiring looks like on the interior fuse block.





Here's how I wired the old GPR for key on power to interior fuse block.


Here's a birds eye view of the engine bay.




I was able to grab switched (key on) 12v power off the trucks main GPR. This is how I am activating the old GPR to send key on power to my interior fuse block. you can see in the above pictured how I routed my wire.



So, to summarize. Starting from the battery I have an exterior fuse block, a breaker and the old GPR that I am using to supply key on power to the interior fuse block. Coming off the exterior fuse block I have two hots that are fused at ten amps each. One hot runs to the breaker while the other hot runs to the GPR. I then make my respective connections coming off the breaker and the switched side of the GPR to the interior fuse block and that's it. Not much to it. Hardest part was brainstorming areas to mount all this. Hopefully I've done a good job explaining this stuff. If I haven't just ask me and I'll try to explain it better. I've covered a lot here and I'm sure there are things I've missed.

I have tested this system and everything seems to be working properly. All items were purchased off amazon btw.

 

I didn't know about the upfitter location. Can you get to your fusebox without removing the glovebox?

If I'm understanding your description, you have a 10 amp fuse going to a 30 amp breaker then through the GPR and finally to your interior fusebox.
Or is the 10A to the GPR just the trigger?

 

Yes, you can get to the fuse box without removing the glovebox. Its easier to have it out of the way for the initial installation.

I can have up to four fused circuits at the battery. I am currently using two. One being constant (key off) hot and the other being switched (key on) hot. Each circuit has it own 10 amp fuse. The constant hot circuit goes from a 10 amp fuse at the battery through the 30 amp breaker and into the interior fuse block. The switched (key on) circuit goes from a 10 amp fuse at the battery through the GPR and into the interior fuse block. The breaker really has no purpose other than giving me the ability to kill the power going into the cab. When I need key off power down the road all I have to do is flip the breaker and I am good to go. Hopefully all that makes sense.

 

This is very crude but should help.

 

Very nice work, I didn't know those circuit breakers came in lower amp ratings, the brand I bought for my winch is only available from 70 amps and up or at least that's what they told me at the electronics store.

 

Well done, Cowboy...old gpr was genius!
I used that grommet for my p/s egt lol and wiring for when i ran wvo

 

Great write up sir! I have been looking forward to this since you told me about it a while back.

I will get this added to the Tech Folder when I get back home and have access to my laptop.

I have a couple of questions that someone may ask if/when going about this themselves.

1. What OEM harness color wires are on the engine GPR lug that you connected your switched power wire to run over to the new accessory GPR and is that a big or small lug?

2. Did you fuse the wire from the engine GPR to the accessory GPR? If so, what size fuse?

3. Wouldn't the 12v breaker serve the same protection purpose as the fuse from the battery going to the accessory GPR? If so, is the fuse/breaker combo short protection for redundancy?

EDIT: I see from your drawing that the breaker is only on the constant hot power wire which makes sense after seeing the drawing.

4. You mentioned 8 gauge wire was overkill, could you recommend a minimum gauge wire for a 10A circuit or an online chart for some to refer to if they were using a larger fuse?

5. Was the 8 gauge wired used to go from battery to external fuse block as well as from external fuse block to the internal fuse block?

6. The two power wires coming off the external fuse block run next to each other physically into the cab with the switched power wire stopping at the accessory GPR first?

Looking forward to the under hood accessory block write up!

 

I’m just over here taking notes on how to properly do a write up...

Nicely done. Very clean!!!!

I like the idea of using the GPR trigger wire for a key-on power source under the hood. I’m pretty sure small lugs get 12v when key is on, but PCM completes the circuit to ground to activate GPR.

I often get constant 12v from the starter solenoid to power relays for headlight harness, driving lights, etc.

 

First let me say thanks for kind words. Secondly, sous I will answer your questions you posted above as soon as I address a problem I found this afternoon.

Long story short I don't think the GPR is going to work in a continuous duty state. That or I have a GPR that is going bad. Here's what I discovered. I monitored the GPR for about 5-7 minutes with the truck idling in the drive. I was checking for heat. I discovered lots of heat. By minute five the GPR was so hot I couldn't even touch it. I then started smelling that classic electrical burning smell. I shut it down and let it cool. I then switched the ground and 12v trigger wires to the opposite posts. Knowing full well that doing that should make absolutely zero difference. It made none. GPR gets incredibly hot. I would not feel at all comfortable using it.

So, I am not real sure why it got so hot? There was zero load on it. I could understand the heat had it been under a significant load. What do yall think? In the meantime I am going to start looking for a battery isolator to takes it place. I might even resort to a square relay if I need to. I was really hoping that GPR was going to work. Perfect factory feel. I think a battery isolator will look the part though.

 

I found this online which may explain the problem, although it is about starter solenoids which are similar in operation it explains the difference between continuous and intermittent duty and why they are not interchangeable. I understand that you had no load on it but perhaps the design of an intermittent duty solenoid is such that the latching coil cannot handle constant duty. https://www.elreg.com/blog/continuou...terchangeable/

 

More info: https://www.oilburners.net/threads/g...y-specs.50798/ On the other hand, the Stancor is rated for continuous duty https://www.dieselorings.com/16-009-...lug-relay.html It must be the latching coils are designed differently, that's the only reason I can see yours getting hot with no load. If you look at the specs for the Stancor it says the coil is rated for continuous duty, the coil has a rating and the contacts have a rating.

 

Well crap...

Although, sometimes no matter how much we planned and prepared a mission in the war zones, there was always a back up and a back up to the back up. It happens...

Do you have the desire to swap the GPR's for testing sake and closely monitor the "new" accessory GPR that was the previous engine GPR?

EDIT: Bigb56 posted before I finished, but if the WR/Stancor is in fact rated for continuous use, my proposed test would not yield valid results.

I am on my phone, so I cannot look back at the images, but I think the engine GPR is a WR/Stancor, is that right?

Did you replace the old engine GPR (new accessory GPR) for a reason or just as a PM measure?

Try removing the accessory GPR line to the interior fuse block and see if the non-existent load being removed makes a difference in the heat produced.

 

Heres ten characters....

 

Thank you for that. I am going to give that a read.

 

Ten characters