RE: GM one wire

["Theo Smit" <theo.smit@dynastream.com>]

If your alternator really only has a single wire, then you do not get the
idiot light function. If you have a three-wire "one-wire" alternator, then
one of the two extra wires connects to the ignition switch, and the other
connects to the idiot light. 

Here's a link that Bob Hokanson pointed up about two months ago:
http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

Best regards,
Theo