[pnt4u2]

I am changing from a 3 wire GM alternator to a 1 wire. What should I do with the "extra" 2 wires? I've been told to tape them off. Is this good advice?

[pepi]

Not really a very good idea, you will have a more reliable charging system with the 3 wire set up . Manufactures are pretty smart about that kind of thing .

[powerrodsmike]

I try to avoid using the 1 wire alternators, contrary to what the manufacturers say , they do draw the battery down. It's not much, but if you don't start your car or keep it on a trickle charger, the battery will be dead in a matter of weeks. I have had to install a battery cutout switch in several cars to keep this from happening. The extra 2 wires can be taped up, although one is an exciter wire, and if you have a charge light on the dash it will not work right anymore.

Later, mikey

[malc]

3 wire - 1 wire comparison.

[T-bucket23]

If you already have the wiring in place for a 3 wire, I would not recommend changing to a 1 wire. They don't work as well as a 3 wire and are not real good at all if you have a lot of electrical accessories. A proper setup 3 wire will help to keep your battery healthy for a long time

[Irelands child]

I just went from 1 wire to 3 wire - and all I've ever done so far with my car is run up and down the driveway. The dam' Powermaster alternator wouldn't kick the charge in until I had 'winged' the throttle over 2500 rpm, which is wrong according to the directions, but now charges at idle or thereabouts.

Dave W

[hduff]

I also want to change from a 1-wire to a 3-wire setup.

The alternator is the one supplied with the Street & Performance harness for my '94 LT-1. It's a polished 12SI; I have no idea how many amps it's rated for and I'm having to rely on the assumption that the boys in Mena, AR know what they are doing. Me, sometimes, not so much. The car has power everything, so I'm hoping it's at least the 94-amp version.

I have read the pages at http://www.madelectrical.com/electri...hreewire.shtml and found them enlightening except for one thing: there appear to be both 1-wire and 3-wire versions of the 12SI. How do I know which one I have or can they all be run as 3-wire just by connecting terminal 1 to a switched 12V source (to excite the alternator; an idiot light appears to be optional) and terminal 2 to the fuse panel distribution point (to externally regulate the voltage)?

My fuse panel is a Ron Francis Advantage (great stuff, but not inexpensive) that does have the yellow diode plug "located above terminals #16 & # 17" per the one page of instructions that I found in the car when I purchased it. It alludes to not needing this when using a one-wire alternator (which is how it is wired now) but doesn't say how to wire it for a three-wire alternator (which is what I want). I'm also missing the plastic strips that actually show the numbers of the terminals, so I'm kinda lost as to what terminal is what (and the location of the panel is, of course, awkward so it's hard to read the printing on the wires). I know I can call Ron and ask about this stuff (another car I purchased had an older version of his panel and they were very helpful), but it's after quitting time today and if anybody knows how to wire the panel for a 3-wire alternator, I'd appreciate the info.

And if it's not clear, I'm weighing in on the side of pnt4u keeping his 3-wire system.

[hduff]

Originally Posted by Irelands child

I just went from 1 wire to 3 wire - and all I've ever done so far with my car is run up and down the driveway. The dam' Powermaster alternator wouldn't kick the charge in until I had 'winged' the throttle over 2500 rpm, which is wrong according to the directions, but now charges at idle or thereabouts.

Dave W

Here's a picture of the back of the alternator.
http://www.madelectrical.com/electri...es/delcor4.jpg

Pull the plug off of the alternator with the engine turned off. Terminal one should read zero volts; terminal 2 should read +12 volts.

Turn the ignition to ON. Both terminals should read +12 volts.

Terminal 1 is supposed to provide +12 volts [only] when the car is running to energize the magnet inside the alternator. If it's not, you get the behavior you describe. If it's +12 volts all the time, your battery will drain when the ignition is off.

I've read that there might need to be some small amount of resistance in the lead to terminal 1 and the idiot light would provide that. But advice varies and it may only be applicable to older GM or maybe non-GM alternators; it's just not clear to me.

[hduff]

If I didn't make it clear, you're measuring voltage in the plug, not at the terminals on the alternator itself.

[hduff]

Just to follow up, on the Ron Frances Advantage panel, alternator terminal #1 is wired to panel terminal #16, alternator terminal #2 is wired to panel terminal #2.

[pnt4u2]

Originally Posted by hduff

If I didn't make it clear, you're measuring voltage in the plug, not at the terminals on the alternator itself.

Thanks for your reply. I finally did get around to check the wiring via recommended procedure and it checked out OK! YIPEEE! No more 1 wire. I now count my alternator with 3 fingers. Not 1. Thank you all for the advice. Once I figure out how to post a picture of my truck, I will do that too.