- Jan 10, 2011
Looked at the bronco parts houses for a 76 3 alternator wire harness and can't find one specifically listed for a 76. I see one for a 66-73. Is there a difference?
best I can tell the wires are good and serviceable. Upgrading the alternator to a 90 amp and wanted to upgrade the harness at the same timeYes. And there are even differences between 66 and 73, so I’m not sure how they can make one fit all of those years.
It’s mostly in the style of connectors, but there might be other minor differences as well.
How bad is yours? And how badly do you want to keep it original looking, versus just fixing what’s there?
I was contemplating a 3G but found a local alternator reman shop with an reman/upgraded 90 Amp Ford 3 wire. I was thinking I could find a beefed up 3 wire harness. Finding that's not the case...For the time being (until you say otherwise) I'll assume it's a modern internally regulated alternator you're going to be using. If that's the case, then you don't really re-use any of the old alternator harness as it will only confuse things and also be under-sized for the new higher output alternator.
So look up any of the many 3G conversion discussions here and you'll get a mess of instructions and advice. But just to add some details here, you basically want a larger gauge main BAT output wire and will run it directly to the battery positive, or positive side of the starter relay/solenoid on the fender. Best practice is to fuse it as well for protection.
Here is the one we sell for 3G conversions: https://www.wildhorses4x4.com/product/Battery_Charge_Cable_AMG_fused/Bronco_Starters
It utilizes a 6ga battery cable style conductor to handle the higher rated units, including the 130a factory style and even higher output versions.
This is the same size that Ford themselves has been using since the introduction of the 3G in 90 and 130 amp models. On some with longer runs, such as vans, or higher loads such as diesel pickup trucks, they use the larger 4ga size cable instead.
So you can make your own, or as you can see you can buy them pre-made as well. Because it's a custom retrofit, it does not matter what year your Bronco is. You're using this to replace your original harness.
Is this what you're contemplating?
Thanks for the advice. Wonder if I should just go with the 3G alternator upgrade at this pointNow that the PSA and warnings are over, you can still install your hundred amp alternator even with the old harness. But you must bypass the main charge wire and instead run a new one up to the battery directly.
Because the run is so short you could even still use 10 gauge wire if you wanted. Eight gauge would be even better, but 10 would be acceptable.
Run a new wire from the BAT terminal to the battery side of the starter relay, terminate the old one safely and you should be good to go.
If you’re not comfortable with Wiring, don’t go in blind. Do a lot of research and listen to a lot of other voices besides mine first.