Alternator question

[jstrong394]

Still running down parts for my Ls swap into my 85 c10. Not sure if it matters but it's going carb'd. Is there a way to have a straight plug and play alternator. I have seen that the alternator for the 5.3 doesn't have the correct connection. Can I run the old alternator with the 5.3 and everything hook right up?

[Matt Cramer]

I just wired the "L" terminal to the alternator warning light wire and left the other three unhooked on my '72 with a stock 4.8 alternator. Worked fine.

[BR3W CITY]

Fbody 1-wire alternators can be made to fit on the truck brackets, but still have to be modified slightly to work.

What is the issue with the 3-wire setup, do you not want to run it to the ecm?

[jstrong394]

From what I have read online I assumed the genIII alternator want work with my c10 wiring harness. I want be using the harness from the 5.3 since I'm going carb'd. I assume that connection on the 5.3 alternator will be different from my c10's connections

[Andy4639]

Originally Posted by jstrong394

From what I have read online I assumed the genIII alternator want work with my c10 wiring harness. I want be using the harness from the 5.3 since I'm going carb'd. I assume that connection on the 5.3 alternator will be different from my c10's connections

The connection them selves maybe differant phiscally but it can still work by using butt connections I would think.

[Revorollerr]

You can utilize a truck style alternator, one wire hook up with the c10 harness. All you need is the constant 12v to the lug and the key on 12v to the plug (can't remember which terminal) It'll require some resistors inline, 470-480ohm iirc. I'd run the truck alternator, they come in a bigger amp than the fbody alternators. Ls1tech has tons of info in the lsx swaps sub forum.

[dayj1]

Originally Posted by jstrong394

Still running down parts for my Ls swap into my 85 c10. Not sure if it matters but it's going carb'd. Is there a way to have a straight plug and play alternator. I have seen that the alternator for the 5.3 doesn't have the correct connection. Can I run the old alternator with the 5.3 and everything hook right up?

The answer depends on which 5.3 alternator that you're talking about. If we stick to 5.3 (truck) alternators, you really only have 2 choices. The regulator will have either 4 pins or 2 pins. You want the 4 pin style. The pins will be labelled "S", "I/F", "L", and "P". "S" and "P" will remain unconnected. "I/F" will go directly to a switched 12V source and "L" will go to either an idiot light or a 470 ohm resistor. The other side of the bulb/resistor will go to a switched 12V source.

For what it's worth, the 2 pin regulators require a PWM (Pulse Width Modulation) signal from the ECM to operate properly. Pretty much all the Gen IV engines (car or truck) have this style of alternator/regulator. If you already have an alternator with a 2 pin regulator, I posted this how-to on swapping out the regulators on the trifive board a while back. It'll set you back about $20, but that's cheaper than a new alternator:

http://www.trifive.com/forums/showpo...62&postcount=1

[Gooker928]

I'm Confused about what you all are saying.
I've done four or these swaps and all I did was hook my 12v alternator wire from my harness to the LS alternator and hook up the starter wires from my harness to the LS starter. The other connector on the alternator goes to the ECU.
Am I missing something? My 78 Z28 has been running like that for two years.

[dayj1]

Originally Posted by Gooker928

I'm Confused about what you all are saying.
I've done four or these swaps and all I did was hook my 12v alternator wire from my harness to the LS alternator and hook up the starter wires from my harness to the LS starter. The other connector on the alternator goes to the ECU.
Am I missing something? My 78 Z28 has been running like that for two years.

The OP is asking about alternator wiring for a carbureted setup. So he's not using the factory PCM and needed wiring instructions for "stand alone" operation of the alternator.

[Gooker928]

Originally Posted by dayj1

The OP is asking about alternator wiring for a carbureted setup. So he's not using the factory PCM and needed wiring instructions for "stand alone" operation of the alternator.

Oh....