First off, let me say that this might work for an '87 and above, but I don't know for sure. I did this on my 86 EFI. all the stock harnesses I've seen for this style are like this, but I have not seen them all!
Things you'll need:
- Wire cutters, wire strippers.
- original bronco alternator harness.
- 3g alternator harness. Part Number M-14305-A351.
- Soldering equipment and heatshrink, or butt splices.
- Eyelet ends.
- Tape or conduit is optional for some, not for me.
Start by unplugging and untaping your stock harness and laying it out to get familiar with all the wires.
Cut off the big alternator plug after the big round junction (it might be a diode or resistor, I'm not sure).
Put on an eyelet end on the wire you just cut. Make sure that it will fit on the back of your 3G alternator.
Cut off the small alternator plug and splice the GREEN wire from your 3G plug onto the green one you just cut from the stock harness.
Cut the yellow one short and cap it with some heat-shrink tubing or some liquid-tape. This can be wrapped up in the harness when you tape or conduit it.
Tape everything up how you like it, and you're finished.
Where the wires go:
- A: On the back of the 3G alternator. This goes the same place as the large power wire that goes to your maxi fuse.
- B: Stator plug in the side/back of the 3G alternator.
- C: To your chassis harness.
- D: Battery side of starter solenoid.
- E: Battery side of starter solenoid.
- F: 3G Alternator.
I hope this helps you guys. I never had a battery problem after this alternator swap.