Would my truck have the wiring in place for the second alternator if it didn't come with one from the factory? if not how would i wire in a second alternator?

 

I believe you would need a complete wiring harness and the associated PCM. Maybe someone here has done this before but I don't think adding the second alternator is as easy as it sounds.

 

I knew it'd be a task, but didn't think it'd be as involved as a complete wire harness

 

The harness is the easy part.

Finding the correct PCM for a dual system may not be.

The regulator for the field winding of the second is controlled by the PCM, not internally like in the single system.

It complicates things.

What are you doing that you have the need for such a large amount of continuous additional current?

Pop

 

This is a pretty good reference. I dont think I would do the install just with his instructions, but seeing things makes them easier to do.

YouTube - ‪Dual Alternator Install 7.3L Powerstroke Part 1 of 4‬‏

YouTube - ‪Dual Alternator Install 7.3L Powerstroke Part 2 of 4‬‏

YouTube - ‪Dual Alternator Install 7.3L Powerstroke Part 3 of 4‬‏

 

Um, I've got dual alternators on my truck and I've swapped pcm's with a truck without and never had any issues.

 

Trey, that's good info to know in those YouTube videos. Thanks!

It's possible the PCM's are all provisioned for duals, and the wiring for the fields is the only hooked up when actually both are present.

Not sure, as I have never found the internal schematics for a PCM. Would like to, though.

Pop

 

Thanks for the links, sure was interesting to watch and shows there is more than one way to skin a cat sometimes. I probably wouldn't do it his way though. It doesn't seem like he posted the 4th video where the electrical connections were made....I wonder if he discovered it didn't work like he intended. If you notice in the 2nd video, he mentioned the wire colors weren't what he expected on the connector, that is because the second alternator has a control wire where the first is a monitor wire. The other connector he mentioned for the chassis cab trucks looks like the same connector used for the auxiliary idle control when the PTO is engaged. I wonder if the factor harness ties into that somehow?

The pulley arrangement doesn't seem quite right either. That is probably why his belt length was incorrect and it was squealing. Looks like he left his tensioner in the original spot and just added a second idler pulley. The factory arrangements does not use the single alternator tensioner at all (see attached photo). His video didn't show it but I bet he figured out that he didn't need the idler pulley once he purchased the HD tensioner. I think it's called HD just to signify it's for a dual alt system, I don't think it actually has more tension but I could be mistaken. I also worry about the 'shim' he used to account for the transmission line bracket. I wonder how he ensured the 2nd alternator was perfectly aligned with all the other accessories. He might find out that his belts don't last very long and have to be replaced on a regular basis.

I'll attach the Powertrain Control System schematic as a pdf under the photo. It shows that the PCM has two pins (#35 and #60). Pin 35 is for Alt #1 and 60 is for Alt #2. I wonder if all PCMs have both pins? Maybe next time someone takes out their PCM they can see if Pin 60 is present and then also look at their harness connector and see if there is a vacant space for a wire. If all PCMs have pin #60, then maybe it's a simple matter of running the control wire from the ambulance harness to the PCM connector. Does the PCM connector come apart so a wire can be added like the under dash harnesses do?

 

Mobile mechanic service and i dont always have a feasable way to power my big compressor so ive got 3 viairs mounted in my tool box that draw 90 total amps

 

I think based on the time and energy involved im just going to save up for a DC power unit to upgrade the alternator i have

 

Does your truck happen to have a PTO transmission? If so, then you could use a PTO driven air compressor and free up a bunch of bed space.

 

Is a gasoline-engined compressor a possibility for your budget? That's far-and-away the most practical.

Pop

 

That wouldn't be out of my budget, but i already have turned my tool box to swiss cheese to mount the compressors, tanks and run wiring in and out of it, so might as well use it, Plus I use it for my air horn, so it's nice to pump up the tanks at the flip of a switch

I'm not sure if the 4r100's came with a PTO provision, Don't think ford started doing that until the torqueshift

 

Ok, I see your sig now....your original few posts must have been via cell phone...
I wasn't sure if you had a manual or auto trans. If manual, then you are good because I think they all have the PTO option by default...

The 4R100 can be had with the PTO option. If you have a plate that looks like this, then you have a PTO trans. This photo is from my wife's 2000 Lariat...

 

Ill have to take a look wwhen i get home, if i have one with a pto would somewhere like a medium/heavy duty truck dealer carry them?