OK, I have a '79 F150 4WD and have been having a grand old time over the past few months fixing it up and getting her going the best I can.

One thing I've recently done is install a 3G 130 amp alternator. I used the harness out of '94 Mustang which has a fusible link that hooks up to the power box but in this case just up to the battery side of the solenoid. I have a 175 mega fuse handy but didn't have a fuse holder.

Someone on a 3G install thread mentioned that they used a 90s T-bird Power Control Box and I thought that was a dandy of an idea. The next time I went out to the pull and pay yard I was set on finding me one. Lo and behold when I arrived there were literally dozens of 90s Tuari and Sables with power control boxes that not only also have the Mega Fuse holder on the side of it but they have room for many more mini fuses, maxi fuses and relays, OH MY! This has got to be even better than a T-bird box for sure!

I got to work clipping wires off the harness as far away from the box as possible and made off for home with my treasure. It's super cool because I'm almost done gathering the parts necessary to install a Mk VIII fan and this means I won't have a engine compartment littered with lone relays and inline fuses. Not to mention I can now start rerouting wiring out from under the dash and setting them up with more modern blade fuses and I don't have to contort myself under the dash if something blows.

At least this is the vision I have for this wonderful little box. Here's the reality I'm dealing with. I'm not a wiring wiz, I actually avoid it as much as possible. When I got the bottom cover (yes, it has a bottom cover too, how cool is that?) off there was a family sized portion of spaghetti looking right back at me. I'm not sure what I expected to find but I have no clue where to start with all this stuff. Is there any kind of guide to how this thing is wired so I know the best place to put different circuits and know what I wont have to move and use to my advantage? I found a diagram of the fuses that go in the top of the box and what they were intended for but that is only limited help for how the wires route on the bottom of the box. There are 2 or three that appear to be jumpers or connectors between different components on the top and I have no clue why.

Perhaps I should start with some of my observations thus far and questions relating to them.

At the mega fuse the cover is labeled "Battery" to the left of the mega fuse and "Alternator" on right. Makes good sense to me but the "Battery" side cable seems way smaller at like a gauge 6 than I'd expect it to be like 4 gauge or so like the "Alternator" side actually is why is that?

There is a smaller, about the same as the Bat wire, yellow/orange wire attached adjacent to the Alt wire that then leads into the box up into one of the circuits then out but with a smaller gauge, same colored, wire and the back into the box again at another point. I'd have thought it would be attached on the other end of the mega fuse like I would have expected to wire up my cab power lead on my truck if I didn't use this box. Is this wire a cab[in] power line and/or can I use it as such now in my truck? One of my objectives is to delete the fusible link my cab power lead is using.

Another problem is that if I use the mounting bracket out of the Taurus it is oriented backwards from how I need it if I put it in the same spot where the voltage regulator was before my new alternator install.

Any thoughts or suggestions?

 

Oldstyle has done it and posted these pics on another thread https://www.ford-trucks.com/forums/1...l#post12303233. He'll be along later to ask my specific questions... hopefully.



Here's some questions to start off with Oldstyle:

It looks to me like you kept the "battery" wire the same and ran it to the battery, I'm guessing that is sufficient since the only current that goes though it is a charge. It looks like you then ran a standard sized cable to the solenoid, correct?

What is the lead off the "alternator" side of the mega fuse? Is it the cab power? Did you keep it and could I use it for that if I wanted to? Should I move it to the other side of the mega fuse?

What do you currently have running through that box and how did you make sure it was wired correctly?

I was thinking of doing a headlamp relay through my box too. How exactly did you/should I do it?

I'm guessing this is on your '78, I've noticed that '79s a wired slightly different than other Dents I might have to modify my set up, are there any signs I be on the look out for so I don't fry something before I finish hooking something up?

I have a multimeter here somewhere but I need to dig it up. It will certainly come in handy but I'm not exactly sure how to run it so if you let me know what settings I need to use along with the readings I should be expecting it would be helpful.

Yes, I'm a complete electrical dope so excuse my bonehead questions.

 

There's a lot of wires and most are for future use. Tape off and isolate un used wires so they can't short out. It looks harder than it is. Just plan each circuit and do one at a time. There are plenty of sockets for most any configuration.

Solder your splices if you want them to last and not be a problem later. I also used silicone and shrink wrap to make waterproof connections.

Click to enlarge:



Take a look at wyckedcombo17's post where I explained the main power battery and jumper to the relays.

Here's some other pics for you: (Mines a 460)



I don't have a finished pic of the Alt to Factory connector, sorry. But I grabbed another harness connector (78) from P&P so I didn't have to cut my factory harness to send "key on/run" power to the new 130amp Alt from the Taurus. You only need one wire. And IIRC you need to make a jumper at the old regulator connection; sorry it's been a while since I did this....

Remember that you loose your idiot light or amp gauge when you do the 3g conversion.

Edit: Original pics from top post:

Click to enlarge....


.

 

Thanks OldStyle that helps a ton. My set up is going to be a little different than yours but there are some similarities.

One question; does this box have a ground in it or would I have to run a separate ground if I need to ground a relay?

The 4 things I want to accomplish first off with the install:

Have a good place for my mega fuse.
Run a blade fuse for my cab power instead of a fuse link. I was involved in a "discussion" about this and want to do it out of principal now.
Run a fuse for my independent Volvo 2 spd fan control.
Run a relay on my BMW dual temperature switch so the fan wont run key off.
Info on my intended fan set up https://www.ford-trucks.com/forums/1...r-dumbies.html

Stuff I'd like to use for the future:

Run headlights through a relay to avoid any under dash fires.
Run absolutely anything I might add without having to do yoga under the dash, especially if it isn't a key on function.

I wold run new wiring instead of cutting up the existing harness. I did slice and dice the wiring involved with the alternator but that is a small separate harness and easy enough to find if the was ever any reason to restore it to 1G alt.

This is how it's currently set up





I wont have a chance to turn wrench on this for another week or so but I'll spend the time planning how to wire the box for what I need.

 

Glad too; but I'm certainly not an expert....

 

I know about the mega fuse that's why I got the box. $15 at JY and tons of room. The maga fuse block @ a parts store is $18+ depending where you find it.

The key on power under the hood is the small lead on the right of the solenoid correct? Can I just splice onto that?

Through my research I should interrupt my temp switch ground with a relay hooked up to the key on power. 2 of the posts on the relay should be grounded should I just run a ground wire out of the box to the fender skirt?

Here is how I've worked up to do my fan wiring.

 

Not sure about that one. FMC400 is the expert here. It is my understanding that of the two sm posts on the solenoid one is from the key sending the crank signal and while cranking the other sends 12v or full current to the IGN system for full voltage while cranking for better starting capabilities. While still hot; it is out of the circuit except when cranking. Using it to power anything else isn't something I would recommend... Power to the coil when the engine is running is of a lessor voltage; at least in a points system. Those benefits with a electronic system serve a different purpose.

I think you can use connector on the firewall near the fan or run a new lead. There's something on the drivers side too but I can't remember what at the moment.

As to the diagram it looks like it should work to me. To the fender skirt would work for grounding.

.

 

I haven't done much lately but I decided to just clean up the box and strip out all the wires. They came out pretty easy and now I can just add in the leads I want where I want them as I go. I now don't have to worry about any loose wires crossing, etc. The little retainers for the wire ends are kind of brittle and I did break a few but the end connectors have their own retention as well and shouldn't be a problem. I can also use some sort of adhesive if I feel it's necessary.

This box is totally modular and I took out the middle block that had the small looking relays in it. I figured I didn't need them.





I went to the wrecking yard today and tore apart another box for the large relay section and pulled out some more of the bus bar contacts to fill in the gaps in the fuse area. I'll be putting the box back together and start wiring it for the few things I want in there for the time being. I need to get some more wire and some shrink tube I'm actually getting anxious to get started on this project some more.

BTW way I found this same box in Explorers, Windstars and Continentals. The only difference is in the number of live slots and the size of the fuses in the box. I actually got a few 60A fuses out of some Explorers the Windstar is almost all 60s but I had enough of them by the time I came across that box.

I saw another box that might work, funny I don't really remember what it was in. I think it was in the Town Car and Crown Victoria. It is more square and might not have as many slots in it but might be a good alternative if desired.

 

I got the box put back together minus wiring. I got the extra connectors for the bus bar and the other relay block in. I forgot that the end block was different and I have no idea what goes into the slots on the right as there was nothing in there when got it and I don't recall what might have been in there on the other boxes.





Straight on shot and a mock up how I'd like to start out. I didn't have the size fuse I want to put in for the LEDs, I'm pretty sure there are 3A or even 1A mini fuses out there I just haven't found any. The others have the minimum that I want to put in those places but might go a little higher as noted. I'm going to wire in the lower key on relay to the headlight relays so I at least don't leave the headlights on in senior moment and drain the battery as quickly. My matchbox is that way and since they are sitting together I might as well hook them together.

 

looks good to me.

 

A little more progress, moved the solenoid and put the mounting bracket in. I just took the bracket when I snagged the box out of the Taurus. I just used the old voltage regulator screws and drilled out the threads on the mounting plate.



Test fit. I'll splice the alternator wires and battery wires when I'm ready. Now I just have to set up my harness and we're golden.



I bought some new headlight sockets so everything from the box out is new. I figured that wouldn't be a bad idea. I'm going to up the wiring a gauge or two out to the headlights too as long as I'm at it.

I found some 2A mini fuses at Pep Boys for my LEDs so all I gots to do now is splice and dice.

 

Hmmm. I didn't think about this when I was pulling alternators. Guess I may need to make another trip to the pick-a-part. It looks a lot cleaner than random relays.

 

Yeah, it is really handy and there's tons of room for anything you want to put in there. I've already found something else to wire into the box, my trailer brake control. I'll probably end up doing a stereo and I have open relay slots if I add any type fog light and such and not have to buy the extra relay kit. I already saved a ton without having to buy a headlight relay kit.

If you do get a Taurus box. Find the one with the most slots that are used, mine had 5 empties so I went back and pulled the contacts out of another box, completely destroyed the thing but they don't care, it is going to the crusher within weeks anyway. I think the Windstar box had all the slots used. Another thing you probably should do is take the alternator wire intact, I went back and grabbed one of those too. The Taurus/Sable cable is something like 4-5' long and you can make it any length you want by cutting and splicing in the middle and leaving the ends intact. The Windstar might be a bit shorter. I haven't shortened mine yet but will as soon as I have everything sorted out. You can either get the small battery cable all the way to the battery or you can just get a short starter type cable and run it to the + side of the solenoid, I did the former but might end up doing the latter if I have problems with how I spliced in the Taurus cable. DON'T FORGET TO TAKE THE MOUNTING BRACKET, it is just two screws on top and one on the side.

 

I finally got the box all sorted out. I ended up wiring things a little bit different than I expected. but it's been working great.

Spaghetti shots:







Looks so much better with spilt loom:

 

I just realized that I didn't put a pic of the inside of the box as it ended up.

Fuses:

Upper left- 20A trailer brakes. I didn't realize it was wired to the battery side of the solenoid until I started installing the box

Upper right- 60A cab power. I have a 80A waiting in reserve if needed.

Lower left- 30A Mark VIII fan. Some prescribe a 40 but the 30 is working fine I have plenty of 40s if needed.

Lower right- 20A Headlights.

Mini - 5A fan sped LEDs. I was going to use two 2A but figured out I only needed one and the 2s kept blowing not sure why must have be resistors in the LEDs.

Relays:

Upper left- high beam headlight

right- low beam headlight.

lower left- key on for the fan. I tried running the headlight relays through it but it didn't work correctly. It must have something to do with how the headlight switch works.

I also put the block for the Bosche type relays back in. They are smaller 20A relays and have non bus bar mini fuse slots, I can always swap it back around if I want to.