How to set up a diode on a 3-wire alternator
 

OK, I was asked by a Barner for this info so I thought I would make it a post. This is how I do it; others can post how they do it.

Radio Shack has a cabinet full of diodes, resistors, caps, etc in the back of the store. Lacking that, or other electronics store, this place has no minimum order:
http://www.digikey.com/

You are looking for a 1N5404 diode. Radio Shack part number 276-1144
rated at 3 amps 400PIV. You could actually use most any diode but I like this one because it is heavy duty.

You will note a band around one end of the diode. That end of the diode faces toward the alternator (diodes are directional). If you get it backwards, nothing bad will happen except the ignition will not turn off, so in that case just reverse it so the band end is toward the alternator. Connect a wire from the band end to the #1 terminal on the alt. (terminal 2 is connected to the heavy post which has the wire going to the battery. A great deal of hoopla is made over so many other places in your car that you can attach the number 2 terminal but in reality all you need do is to connect it to the heavy terminal that goes to the battery. I like to keep it simple, and no one will die if you do it this way :)). If you do not have the special 2-terminal plastic connector for the alternator, just use crimp-on female spade terminals, which I do all the time. Be sure to slip some heat shrink tubing down over the entire female spade so that it can never touch the case, else you will blow your 30 amp fuse and blow the diode.

Now for the potential problem area: you need to connect the other end of the diode to a terminal or wire somewhere in your car that is live only when the key, or ignition, is on. Depending on how you have your ignition set up, this will vary. I am not using a true pop-out ignition switch, so I connect mine to the hot side (key side) of the coil.

If you are away from home and for some reason the diode fails (never had it happen yet but never say never), just use a jumper (see Tom W's recent post on these) to bypass it; or cut the diode out and join the two wires together. The only downside will be that you cannot turn the engine off; no problem, this is a temporary fix anyway, so just remove the jumper or unjoin the two wires, and the engine will stop immediately (if you have the key off of course)

It takes way longer to write this up than it does to do it!
have fun:)

Re: How to set up a diode on a 3-wire alternator
 

Thanks.
I might add if the diode fails just touch the #1 or R terminal to battery for a second, like polarizing. It will continue to charge as long as the engine is running. If B+ is applied the #1 or R it will create a drain if the car is not running, be aware of that.
Once excited the trio will feed the VR. A small bulb will work in place of the diode. The #1 or R terminal is an output and if it see any load above 3 amps it will kill the diode trio in the alternator, a simple repair.
As to the #2 or F terminal it is just a sense terminal or a reference as to the battery state of charge. I only bring up as many people here have modified cars. T-Bird is quite right, loop it back to the alternator (machine sensed), but for those that have a battery in the trunk tie #2 or F directly to the battery (battery sensed).

Re: How to set up a diode on a 3-wire alternator
 

Mike, what exactly is the purpose of the very lightweight diode trio? The other diodes are the usual rectifying diodes and their function is easily understood. Not so much the trio....
thanks

Re: How to set up a diode on a 3-wire alternator
 

Thanks to you for the write up. The SI series would not be my choice but they are inexpensive and available.
I see what some one wire SI alternators go for and you have provided an explanation of how to receive (actually better) results at a third the price. Not only that, the factory three wire set up means you can do a quick change on the road as opposed to trying to find a one wire. Your point!

I have been in the business 35 years and many people run away if it is electricity. Defined in readable terms as you have, others should see no problem embracing the concept.
All of thisdeserves a thank you

I would also say as the owner of a small electrical shop folks would be amazed at how helpful we/they can be....

Re: How to set up a diode on a 3-wire alternator
 

This may help as well;

Re: How to set up a diode on a 3-wire alternator
 

perfect

Re: How to set up a diode on a 3-wire alternator
 

So what, if there is no option for a minimum quantity, look at - https://www.icrfq.com/ it will enable you to locate the required item you require or search on google for your requirements and put your trust in the Google divine beings and expectation you get great data before you get it.