|Ford Ranger Forum||Tech Articles||Other Articles||Featured Rangers||Readers Rangers||Classifieds|
Ford Ranger 2.8L 130 Amp Alternator Swap
I have done 130 amp swaps into Fox Mustangs, and looking at the 2.8l motor in my 1984 Bronco II, it looked pretty simple. All you need to do is go to the boneyard, and grab an alternator and alternator harness from a 1994/1995 Mustang V6. The alternator is a direct bolt in, and the harness is the perfect length, as well as having fusible links built into the heavy gauge power cable. The correct 130 amp alternators were also in 93-96 3.8L Thunderbird/Cougars, but you still need the Mustang harness as the Tbird/Cougar ones don't have the fusible links in them.
This swap should work for any of the 2.8L Ranger/Bronco II's. Its a pretty simple swap. The 94-95 V6 mustangs had 3.8L motors. You can get these alternators off of early 90's 6 cylinder full size truck and vans, too. There are various amperage Ford 3G alternators, but all the 94-95 V6 Mustangs had 130 amp ones. There also were many mounting differences too, but just grab one that has the mounting "ears" 180 degrees apart like the stock Ranger/Bronco II alternators. I was able to swap the stock Ranger/Bronco II v-pulley to the new alternator as well. You might have to scrounge up a nut and bolt for the top mounting ear for the 3g alternator, as some had threaded holes and some didn't. The bottom ear bolts straight up to the stock Ranger/Bronco II engine bracket.
At the junkyard, find your victim Mustang. Grab the alternator, and the wiring harness that attaches to it.
Strip the plastic wiring loom from the harness.
Follow the wires from the alternator to the car, and just unbolt the big eye terminal from the starter solenoid. The big black/orange and the yellow/white wire both go to this terminal.
Follow the green/red wire as far into the engine bay as you can, and cut off as much as possible.
So now you will have the alternator with the harness that has the plugs on one end, and the other end has the eye terminal with the black/orange and yellow/white attached to it, and a good length of the green/red wire.
Back at home, unhook the harness from your stock alternator.
Remove the wiring loom all the way back to the firewall.
There is a wire that goes to the choke heater on the carb. Snip that off from the alternator harness where it splits off.
Follow the smaller wires to the voltage regulator. Unplug it, and toss it into the trash.
Cut the green/red wire off right at the regulator plug. There is also a wire that runs to a small capacitor from the regulator. You can trash that too.
If you look at the charging system wiring diagram in the tech section, you should be able to follow along here.
You can throw away the harness that goes between the regulator and alternator.
Now follow the big orange/black wire that was on the alternator back to the harness coming from the firewall. There is lots of loom and electrical tape to remove here to get to where you have to go. You want to go all the way where it branches off from the other black/orange wiring.
Cut the two ammeter wires. One is yellow/green, and the other I believe is red/orange. Also cut the last wire here that goes to the voltage regulator plug. I cant remember it's color.
Basically you are removing all the stock alternator wiring here. Like cutting dead limbs off a tree. Cut what is left of the black/orange wire off at the splice, but leave the other big black/orange wires alone.
Again, look at the wiring diagram, and once you get into the job, you will see what I mean. The only thing you will have left from the stock wiring is the green/red wire cut off from the voltage regulator plug, and the 2 ammeter wires dangling loose.
Now mount up the new alternator and plug the new harness in.
The main cable eyelet just bolts onto the battery side terminal of the starter solenoid.
The green/red wire you just splice into the green/red wire you cut from the voltage regulator earlier. You might have to use a scrap piece or wire to extend them. Please solder and shrink wrap these, as you don't want a bad connection to leave you stranded someday.
Ford charging system colors were the same for many years, making this kind of swap that much easier.
The pigtail for the carb choke heater can be spliced into the green/red wire also.
Loom everything back up. You can just leave the cut off ammeter leads. Just loom them back up with the rest of the harness.
That's all there is too it. If you loom everything back up nice, it will look like Ford put it there to begin with. Obviously this will make your ammeter no longer functional, but they are pretty useless as indicator of how your electrical system is functioning anyway. Plus, they can be a fire hazard, which is why they don't put them in cars anymore. I mounted a small voltmeter in the front of the center console to keep an eye on things.
These diagrams are from a fullsize Ford Bronco, but the wiring is the same updating to a 130 Amp alternator.
Basic schematic of old charging system
More detailed schematic of old charging system
Basic schematic of new charging system
More detailed schematic of new charging system, showing how to integrate with the old wiring.