Wiring a GM alternator? (1 Viewer)

[Corbet]

Could some one give some detailed wiring instructions for a GM alternator into FJ60. I thought I had it right but almost melted the wiring harness on the test drive.

 

[cruiserbrett]

A: figure out what "GM" aternator you have(ie 10si, 12si, 28si, cs130, cs144, etc)-they're not all the same for wiring...
B: search!

 

[gifu]

not sure which one you have, but I will say this: upgrade to main wire (that is, the wire that actually carries the juice back to the battery). A GM alt will fry the stock harness if you let it try to charge through that teeny stock wire. You can leave the stock one connected, if you like... but run a heavy gauge (100A would be like 4 gauge) wire directly from the alt to the battery.

ask me how I know: (Rubicon 2001, night run, all lights and heater blowing... blew the fuse, the fusbile link, and killed a yellow top.

 

[CRZRJames]

Try http://www.madelectrical.com/index.shtml for alternator wiring issues. Buy his kit for the instructions, it's a bargain. He advises using the 10SI or 12SI because he likes the 3 wire hook-up.

It's worked in my '74 FJ40 for several years and well supports a dual battery setup and long winching sessions.

Good Luck,
James H

 

[JDay]

I pulled a GM alternator out of Caddy in the junkyard (looks brand new) for around $20 last year. I googled the part number on it to figure out what it is.

I ran it in my 87 FJ60 with a new primary wire from the alternator to the battery (4 gauge if I recall) for about a year. I kept getting an overcharge situation when I had too many things running, ie lights, wipers, stereo. It never went past 15V, but it always worried me.

This weekend I went through and figured out where I screwed up. I tried to reuse some of the wires that signal the alternator to run.

One wire alternators are simple. Most have 4 connectors (S, F, L or I, and P) and the charging post (B).

You only need to connect from the B post to the battery and switched ignition to the L wire with a light in series. The only other you could use is the S wire to "sense" the voltage to control. The F = "Field" and the P = "something I forgot" are not needed.

I was not able to get enough voltage to the L wire on the alternator just supplying a wire from a switched ignition source (the black/yellow wire on to the coil). I ended up wiring the switched ignition wire to a relay and supplying a heavier wire from the battery through a light that I mounted in place of the stock light in the dash to the alternator. Works perfectly now and no more overcharging.

I think the problem with using the stock wiring is the loss of too much voltage; ever notice how much your stock voltmeter fluctuates? The loss of voltage makes the alternator "think" it needs to charge more.

Try this link for more info http://www.alternatorparts.com/cs130_sbpage1.htm

 

[Corbet]

It is a three wire. The truck is in a friend's garage, can't go and look now.

 

[Corbet]

Looks like a 10si