I am starting the planning phase of installing an onboard compressor. I am thinking of mounting the compressor and manifold (no air tank) above the spare tire to keep it out of the elements. I haven't chosen which compressor system I am going to go with yet for my FS airbags, but I have looked at several and most say to run the power either to one of the batteries or to the fuse box next to the under hood fuel filter. So...I was thinking (not always a good thing) maybe there is an ignition key operated 12V source in the rear. Maybe one of the 7 pin connector wires I could splice into? (I have the Ford hitch prep and in bed connector). Seems like it would be a lot easier to use a power source back there than going all the way forward in the truck. I am leaning towards the Air Lift Wireless One and if I use that one I would not have to go forward with anything, would just the "FOB" for pressure indication and control in the cab. Any thoughts and/or advice? -Glenn

 

If you have an upfitter available, I'd say it is worth the effort to run a dedicated power line off one of the upfitters to the location of the compressor. I would not tap into any existing power sources. That's my opinion. It doesn't take long to run the wire and it's the safest way to do it in my opinion.

 

What he said ^^^^ and if you don't have upfitter switches they can be added.

 

There is a power/charge pin in the 7 way trailer connector. This circuit has it's own fuse and relay and is rated at 20A, much like the upfitters. There is a delay before power is applied after the engine is started. The engine must be running to have power, not just key on (acc.). This circuit is like this as it was designed to charge a battery, and not drain the truck batteries if key is left on.

That being said, if you want to fill bags with engine off you'll need to find another source perhaps the upfitter mentioned above.

 

Thanks guys. I do have upfitter switches in this truck and I had them in my '08 F450 as well. I tried using one of them in my '08 for my TPMS system and never had any luck getting it to work. I found what I thought was the correct dead ended wire bundle under the dash (using several different drawings and pictures found here on FTE), stood on my head under the dash for what seemed like eternity with a multi meter trying to find one of them with power when I flipped the upfitters on (tried all four), and was never successful. I guess I still don't understand the upfitters very well (not much of an electrician). I was hoping to avoid that pain again. I had a good ground down there for my multimeter and tried every one of the dead ended wires in that bundle and just could not get any of them to show any voltage when I flipped any of the switches. The little light on the ends of the upfitter switches were working fine, so I assumed the upfitters had power. I also verified the correct colors of the wires from the pictures and drawings I had. Once all the blood had rushed to my head from working under there things got fuzzy and I just found another wire under the dash with key on power for my aftermarket TPMS.

 

Given what you just said, I would encourage you to have the system wired by a dealer or tech that does understand the upfitters and the wiring of these trucks. It is flat out dangerous to start tapping fuses or wires on these trucks if you are not certain of what you are doing and even then it can be an issue. The tech folder is full of the information to do it yourself, but if you've already looked at it, I won't rehash it for you again.

If you don't want to go that route, install everything and run the wire into the cab of the truck for the power lead for the compressor and just take it to a tech to have that hooked up and verify your wiring is correct. That will be less than 30 minutes and well worth the once over by someone that knows how to do the connection properly. This kind of service is not a problem at most dealers and they welcome it. It's quick and easy and not that expensive.

 

Thanks Savage, I may do just that. I just went back into the tech folder and found a couple of great videos on just where the pass thru and up fitter wires are. I won't attempt it unless I am sure of what I am working with. -Glenn

 

If you want help, let someone (I volunteer) know

 

Thanks Savage. It would be a lot easier to work under there if I wasn't in my 50s. Not as limber as I used to be. -Glenn

 

the lights on the end of the UF switches are controlled by the UF unit power. the power THRU the relays behind each switch come from a different fuse. so the lights mean nothing..

using the UF and passthru wires is a pain cause they need to be 6 inches longer so someone can SEE them AND reach them at the same time.

some have said the easier access to the engine bay side is to remove the wheel liner at the drives front wheel.. I know its crazy tight otherwise..

I use UF 1 to control the compressor, UF 2 for the valve at my aux tank,
and UF 3 for my light bar. all three use a passthru wire

 

Thanks again Sam, I can always count on you for good info as well! -Glenn

 

I just installed the Firestone bags and airlift compressor. I used one of the unfitted switches to power my compressor. So it only works when the truck key is in the on position and the up fitter switch is up.

 

Okay, here is what I am thinking...
Instead of splicing into any of the potential power sources around the 7 pin connector I think I will go forward and use upfitter switch #1 (25 amp). I believe I will ground the compressor back on the frame somewhere near the spare tire (there are a couple of ground spots back there) and run the positive line forward tie wrapping it to the frame rail up to the transmission area on the drivers side. I will then run up under the hood and find one of the pass thru wires. I will splice the positive wire with the positive wire from the compressor and put heat shrink on it. I will then go into the cab, find the other end of that same pass through wire, find #1 upfitter switch wire (yellow) and splice those together. Does that seem to make sense? -Glenn

 

Get it done before you hit your 60's. (Trust me)

 

Red- I plan on having it done well before that, but thanks. The truck would be too old then!