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I need to put in some circuits for upgrades such as heated mirrors and heated seats. Need some battery and ignition active circuits. Is there a preferred approach, glad to get some ideas. Thanks.
So I’ve been looking around under the dash. I found the fused “29” wire and the 4 customer access wires that pass thru the firewall. My truck didn’t have the heated mirrors or heated seats that I’m trying to add but I have a 20 amp fuse in slot 9 for heated mirrors and a 30 amp in 109 for heated seats. So I would love to know how to tap in these circuits. Are they wired and where would they be terminated?
So I’ve been looking around under the dash. I found the fused “29” wire and the 4 customer access wires that pass thru the firewall. My truck didn’t have the heated mirrors or heated seats that I’m trying to add but I have a 20 amp fuse in slot 9 for heated mirrors and a 30 amp in 109 for heated seats. So I would love to know how to tap in these circuits. Are they wired and where would they be terminated?
What's the amp draw on the heated seats? This will determine if you can use them customer access wires as a feed wire or not. The wires are quite small and personally I wouldn't use them for much more than switching a relay or very low amp draw.
In any case they are attached along the loom that runs below the wipers in the engine bay.
One of the customer access wires is hot when ignition on. Keep that one in mind for switching relays on and off
The mirrors are only a few amps. 3.5 tops depending on which ones you get. Are you wiring them up to be permanently on or on a switch so you can turn them off?
If it was my I would run a fused (or manual reset circuit breaker if you like) feed wire of a decent size directly from battery to inside the cab. You then have the option of adding to it later. Have a look along the firewall or up under the dash. There are a few spots you can poke wires through.
Use a relay for the heated seats and another for the mirrors , Ignition on wire I talked about earlier to pin 86 via a switch , ground to 85, battery feed to 30 and use 87 to the mirrors or seats.
So I’ve been looking around under the dash. I found the fused “29” wire and the 4 customer access wires that pass thru the firewall. My truck didn’t have the heated mirrors or heated seats that I’m trying to add but I have a 20 amp fuse in slot 9 for heated mirrors and a 30 amp in 109 for heated seats. So I would love to know how to tap in these circuits. Are they wired and where would they be terminated?
I don't have the wiring diagrams or fuse panel layout in front of me, but if you are sure those fuse locations are only for accessories that your truck is not equipped with, you can use them if you like. Go to the back of the fuse panel and tap into the circuit if your choice or isolate and reroute the circuit for your use to your new accessory.
Use a common or unique ground point near the accessory you are installing.
Your best bet is to use a fuse/relay block for current and future accessories. Use switched power and a decent gauge wire directly from battery with an inline fuse.
Thanks for both replies! I was aware that the customer wire on fuse 29 is only 10A and ignition switched. I will use this as a trigger for some future stuff but focused on the 2 current projects.. I think the next step is to pull the batt terminals and the fuse box to have a better look and see if I can ID the wires associated with the fuses that are supposed to be powering these circuits already. My truck is a Lariat, assume it had a more populated wire harness? I was kinda hoping these were terminated somewhere near the destination, but I can run new if needed.
Long term, I’m eyeballing the space to the right of the fuse box for mounting a small auxiliary fuse box with a new fused supply right off the battery. Saw some with some fuses and a couple relays, that is probably a good combo.
if you are sure those fuse locations are only for accessories that your truck is not equipped with, you can use them if you like. .
Genius advice Sous! I pulled the fuse box and ohmed out suspect fuse locations to map the connector pins on the back of the fuse box and compared with the wiring harness to see if it was wired or empty. I found a great deal of empty slots..
Here is the list of circuits fused in the box that don’t go anywhere:
Fuse 2 PowerPoint console 20A
Fuse 3 PowerPoint 3rd row 20A
Fuse 9 Heated Mirror 20A. (This one isn’t connected to the Batt wire stud on the fuse box, hoping it is a delayed circuit?, may not have power supplied to it?)
Fuse 15 Power memory 10A
Fuse 21 Rear wiper 25A
Fuse 108 Aux Blower motor 40A
Fuse 109 Heated Seat 30A
Fuse 114 Passenger power seat 30A
If most/all of these work out, I may skip a dedicated sub fuse box….
I have to hit the junkyard and grab some wiring to put additional connectors in my harness. I’ll make some deadheaded wires like what ford did so I can wire in as I need to …
I’ll update once I get this project further along.
On an interesting side note adj pedals and air suspension did have factory wires leaving the fuse box despite my truck not having either of those options…
Ran into a snag…junkyard crushed everything in my era. Went to the Ford dealer trying to buy terminals or pigtails for the 3 different terminal types on the back of my fuse box. If anyone snows sources/part #s etc. that would be greatly appreciated. The areas with masking tape show locations of the fuses I traced out that aren’t wired.
If not, it will be going back together as is for now until a scrap donor shows up at the junkyard.
Figures it would trace back to multiple connectors with all 3 terminal types!
Genius advice Sous! I pulled the fuse box and ohmed out suspect fuse locations to map the connector pins on the back of the fuse box and compared with the wiring harness to see if it was wired or empty. I found a great deal of empty slots..
Here is the list of circuits fused in the box that don’t go anywhere:
Fuse 2 PowerPoint console 20A
Fuse 3 PowerPoint 3rd row 20A
Fuse 9 Heated Mirror 20A. (This one isn’t connected to the Batt wire stud on the fuse box, hoping it is a delayed circuit?, may not have power supplied to it?)
Fuse 15 Power memory 10A
Fuse 21 Rear wiper 25A
Fuse 108 Aux Blower motor 40A
Fuse 109 Heated Seat 30A
Fuse 114 Passenger power seat 30A
If most/all of these work out, I may skip a dedicated sub fuse box….
I have to hit the junkyard and grab some wiring to put additional connectors in my harness. I’ll make some deadheaded wires like what ford did so I can wire in as I need to …
I’ll update once I get this project further along.
On an interesting side note adj pedals and air suspension did have factory wires leaving the fuse box despite my truck not having either of those options…
Originally Posted by WNYPSDguy
Ran into a snag…junkyard crushed everything in my era. Went to the Ford dealer trying to buy terminals or pigtails for the 3 different terminal types on the back of my fuse box. If anyone snows sources/part #s etc. that would be greatly appreciated. The areas with masking tape show locations of the fuses I traced out that aren’t wired.
If not, it will be going back together as is for now until a scrap donor shows up at the junkyard.
Figures it would trace back to multiple connectors with all 3 terminal types!
The heated mirror fuse location I doubt would be a timed circuit. From what I have read most times with the F series they have just had the mirror heat running all the time. If there was actually a button installed , usually the button itself has the timer circuit built in.
Honestly the simplest and best way would be adding the Auxiliary fuse box like you had already talked about. Least you know what is running where, what load it can take etc. Easily upgradeable too for other functions later on and troubleshooting would probably be easier.
IMO trying to piggy back off the factory fuse box and wiring will end up being a pain. If you want to add to it, it's not so straight forward like you are finding now, let alone the time it will take to adapt to it
So following up now that things are back together. I think the space to the right of the fuse box is a good spot for a small aux fuse/relay box in the future. For the meantime, I went ahead and wired in blunt cut wires for all the fuses listed above. As I thought from using an ohm meter, fuse #9 was not actually connected to power, but all the others worked and I have 7 new circuits fully fused. I grabbed a scrapped out fuse box wire harness off EBay and pulled some terminals with wires out of it. You need to remove the red locking tabs from connectors to remove terminals, but on the truck fuse box, the terminals will slide back in without pulling them, so its an easy in-truck job to add wires in the spots where they go. I blunt cut and heat shrink wrapped them and added a Brady wire marker with the fuse number for future use. I did wire the heated seat immediately since that is what started the whole thread. It’s a shame the heated mirror fuse is dead, that was my other immediate wiring need, I will just use one of the other circuits instead. I will print some stickers and update my owners manual as I use any of the circuits. Some work - yes, worth it -yes.
Blunt cut wires wrapped and labeled after adding to the fuse box
This is great information to have - sounds like you would not need an extra fuse panel with all of these extra circuits available, unless you exceed the input wire current capacity. Very nice - thank you!
All of new available circuits are battery hot, so I am still thinking about a small fuse panel that is ignition switched thru a relay. My heated seats called for battery hot, so that was perfect. It uses a relay under the seat and an ignition switched trigger wire.
I didn’t check every fuse location against my wiring, only the options I really thought I wouldn’t have on my truck. That is the time consuming part - tracing fuses then checking the truck harness and making sure you have the right connector and right pin.. Obviously every truck is different with various options, so the number of available circuits might be higher or lower than what I found. It really appears that my fuse box is the same one as an Excursion judging by the fuse locations populated to the back of the fuse panel- maybe because mine was a Lariat pkg? Not sure how many different fuse boxes Ford might have used?
I wish new pigtails from Ford was an easy option, but the scrapyard route worked well. There are only a few different type terminals on the fuse box, but the wire gauges in the donor fuse harness ran from skinny to pretty robust. I picked out the fatter wires to use for my pigtails.
Short update. I am researching the newer truck upfitter switches along with the 05 lower dash with small glove box. It appears that they utilize a number of the hot spots I found to source power so these are legit. Here is a link showing the connector in question. On my trucks fuse box that connector was there and already in use, but sparsely populated. https://dieseldatabase.com/installin...d-super-dutys/
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