Alternators: carb 3 wire efi 4 wire why?

[AccordB20A]

yeah i searched but cdnt find anything i need a quick answer whats this extra wire for and is it needed to make the car run????

reason is i have 2 b20a accords with 2 blown alternators, i have one spare but my other spare is from a b18a carb engine

[A18A]

i think 1 is for the ecu!??!?!?!?

[LX-incredible]

The fourth is used for the ecu to sense the load on the alt and step the idle up accordingly. It will probably run, but it might throw a code.

[AccordB20A]

ohhh thats interesting i didnt know my car was that brainy!!, and yes a18a you allready told me it goes to the ecu......now i know what it..could...be fore :D

[russiankid]

The fourth is used for the ecu to sense the load on the alt and step the idle up accordingly. It will probably run, but it might throw a code.
This could explain why my LX idles at 750rpm with electrical load.

[MessyHonda]

lx-i=smarter...hehe jp you carbed guys

[AccordB20A]

well im gunna be running a carb alt on the accord im selling so ha to the poor guy tht buys that

[russiankid]

well im gunna be running a carb alt on the accord im selling so ha to the poor guy tht buys that
It just makes the engine idle lower, makes it sound more of an actual pur.:welcome:

[carotman]

You can swap the voltage regulator between the 2 alternators. They usually don't die. This way, you can turn the B18A alternator into a B20A easily

[A18A]

i think thats the part that fugged out on him?

[POS carb]

I've run a 4-wire 1997 alternator on my carbie a20. It will charge with just the black/yel wire connected fyi

[AccordB20A]

man ive learnt so much since creating this thread!

[carotman]

man ive learnt so much since creating this thread!

This is exactly why this forum was created :D

We all have been newbs one day!