2G alternator wiring repair (and aero-airbox install)

[interceptor1985]

That's okay, it's really helpful cause I don't have electrical know-how. Simple as some of the wiring is in the case on the 3g conversion, I obsess to make sure my car doesn't burst into flames. I read somewhere, maybe tbird or thundercoupe forums that someone's car did catch fire after the 3g, how, I haven't a clue.

Thats a good thing...Then later after you did it right...other peaple could ask you about it

[gadget73]

actually you want finer strands if anything. More flexible, and you end up with more copper for a certain gauge since the strands fit together closer.

Only reason you'd possibly have a fire post-conversion is not fusing it, or using too thin of a wire. I tried it with an 8 gauge, and it got hot. Replaced with 4 ga and the proper ring terminal at the alternator so it fits nice, no more problems. I don't use any of the stock wiring for my alternator, didn't feel like trying to figure out the proper fusing with the existing wiring plus new. Figured it was just easier to ditch it all and run a single fuse (well, breaker in my case) so I didn't have to worry about it.

[1987cp]

Figured it was just easier to ditch it all and run a single fuse (well, breaker in my case) so I didn't have to worry about it.

What'd you use for a circuit breaker?

[86GmLsCoupe]

I agree with ditching the stock wires, thats what Scott said I should do. I figure, in the event the mega-fuse in the new cable blows (which I doubt), the stock wires would have to bear the full load and thats just seems like a fire waiting to happen. I never want to have to mess with that harness that goes around the front in the header.

As for the car that caught fire, I don't know if the guy never fused, spliced 10g from the alt post into the original black/orange wires, or had some kind of runaway thermal failure. Scott was saying a breaker would be good to use because they are resettable in the event you get stranded. I was looking into the ANL wafer fuses, and I even saw some that have a digital readout, but I dunno if that's helpful or a waste.

The only wiring change I'm confused about is I read that you leave the old black/orange wires off the new alt, but you have have to keep them connected at the starter solenoid or you'll inadvertently disconnect the yellow battery sense because they share a fuse link? Basically, leave the starter solenoid alone. If I leave them connected there what/how do I cap them off because won't they be live?

[gadget73]

What'd you use for a circuit breaker?

150 amp cb that i found at advance. they're like 30 bucks, but if something happens, I can just reset it instead of being stranded if I don't happen to have a spare fuse. Also, I couldn't find a fuse at the parts store over 60 amps.

[gadget73]

I agree with ditching the stock wires, thats what Scott said I should do. I figure, in the event the mega-fuse in the new cable blows (which I doubt), the stock wires would have to bear the full load and thats just seems like a fire waiting to happen. I never want to have to mess with that harness that goes around the front in the header.

As for the car that caught fire, I don't know if the guy never fused, spliced 10g from the alt post into the original black/orange wires, or had some kind of runaway thermal failure. Scott was saying a breaker would be good to use because they are resettable in the event you get stranded. I was looking into the ANL wafer fuses, and I even saw some that have a digital readout, but I dunno if that's helpful or a waste.

The only wiring change I'm confused about is I read that you leave the old black/orange wires off the new alt, but you have have to keep them connected at the starter solenoid or you'll inadvertently disconnect the yellow battery sense because they share a fuse link? Basically, leave the starter solenoid alone. If I leave them connected there what/how do I cap them off because won't they be live?

I got rid of all of that on mine. The yellow, the black/orange, and all that is cut at the fender and unhooked at the solenoid. Someday I'll rip all that wiring out but its bundled into the headlamp harness and I haven't felt motivated to tear into it that far. If you want to run battery sense direct to the starter solenoid like the factory setup, I'd personally just run a new wire zip-tied right to the new charge lead. My battery sense lead is like 3" long and actually connects right to the charge post on the alternator. Probably not 100% ideal but my voltage is fine, right about 14.1 and I'm OK with that.

[1987cp]

That reminds me, my 2G wiring is a functional duplicate of the factory stuff and I'm seeing a voltage drop at idle when the lights and HVAC fan are on, but not when they're off. Voltmeter swings right back up to 14 when I blip the throttle to about a grand. Thoughts on that?

[85crownHPP]

thats normal... and expected. the alt candle handle the load, and they dont produce much at idle...

[gadget73]

What he said. Poor low rpm output characteristics.

[86GmLsCoupe]

I gotcha Gadget, so you took out all the old wiring but redid the yellow battery sense. I think I'm going to disconnect them at the alt, cap them somehow and just leave the harness intact. So long as they're not used by the alt itself they should pose no hazard, the only thing is since they're still on the starter solenoid, aren't they live? I don't see how the black/orange and yellow are tied together, before the solenoid I see them come out and they have separate fuseable links. The only thing is they are on the same post so if you took the charge cable off, just be sure to put the yellow back on. Does that sound right to you?

[CheeseSteakJim]

Just, uh, hypothetically... what if you didn't upgrade the engine-to-frame ground with a 3g conversion? Could that cause a fire?

And now that I mention it, where is the engine-to-frame ground? And how do we measure loss over specific cables? Just measure the voltage at one end and then measure the voltage at the other end?

[86GmLsCoupe]

From the differet 3g guides I've read, you must upgrade the ground even though some don't mention it. When you add the 3G alt., you need to upgrade your "Big Three." Below is some information from the12volt.com about the wiring upgrades and grounds.

"The "Big Three" upgrade means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis. Some people replace the factory wiring; others add additional cables to the factory wiring.
NOTE: Realize that the "absolute ground" of the electrical system is not the battery negative terminal or the vehicle chassis, but is the case of the alternator itself. This is why perhaps the most important cable among the Big 3 is the engine ground strap, as this is what connects the alternator ground to the vehicle's chassis. Be certain the resistance between the alternator case (the engine block assuming the alternator is properly bolted to the engine) and the battery negative is minimized. (Thanks to the12volt for pointing this out!) (http://www.the12volt.com/installbay/forum_posts.asp?TID=73496&PN=1)"

[CheeseSteakJim]

I upgraded my positive cable and my engine ground, but not my chassis ground... that's why I'm asking. I'm already grounding out the alternator case. Do I really need to replace the chassis ground too?

[85crownHPP]

Id say yes, considering all your electronic everything grounds to the chassis.

[gadget73]

I gotcha Gadget, so you took out all the old wiring but redid the yellow battery sense. I think I'm going to disconnect them at the alt, cap them somehow and just leave the harness intact. So long as they're not used by the alt itself they should pose no hazard, the only thing is since they're still on the starter solenoid, aren't they live? I don't see how the black/orange and yellow are tied together, before the solenoid I see them come out and they have separate fuseable links. The only thing is they are on the same post so if you took the charge cable off, just be sure to put the yellow back on. Does that sound right to you?

On my car, all 3 went to the same ring terminal. Its all unhooked, the ring terminal with all that wiring is laying next to the battery.




Ground upgrades are also a good idea. I installed a new battery to engine ground when I replaced the motor the first time, but the engine to body grounds are original, and my car never had a battery to body ground. Still doesn't have one actually.