I have a 91 civic dx and have been having charging issues. I decided to replace the alternator only to find that someone that had owned the car before me had cut off the green plug that goes into the back of the alternator. I still have the big white wire under the nut. If I'm right this should mean that the alternator is charging all the time - right? Does the 4 wire green plug control the alternator output as to the load and the battery state of charge? Does anyone know where I can get a green plug? Dealer wants to sell the whole harness. Does anyone have the wiring diagram/color code for the green plug? The terminals look standard size if I knew what color wire went to which terminal I'd just make my own connector. I'm new here to this forum but if anyone could help I'd appreciate it. No modifications - just an old beater, all I could afford. Thanks in advance and may God bless.

 

If the factory label is still on the alternator it has a key to the pin-out. You have to at least supply battery voltage (switched by the key) to the "I" terminal for the alternator to work properly. This will be a black and yellow wire. The "L" terminal is for the warning light on the dash. The other two go to the ECU and I think they are not absolutely necessary.

But if the wires are still in the harness, just cut a plug out of a parts car and splice it back in. I think the same plug was used from 1988 up to at least 2000.

 

88-95 share the same plug (OBD0 and OBD1). The plug changed when they started using OBD2 technology. Integra and Civic share the same plug, as the Integra alternator can be used in the Civic chassis (and vice versa) and has a slightly higher output.

Never thought I'd be able to add to one of your posts! :P

 

Thanks guys, good info so far but there s still a couple of issues. It appears that this is an aftermarket alternator and I don't see any info as to pin identification. I don't have a parts car so I'd have to go to a junk yard and I'm not too sure just how willing they would be to let me clip a plug off a harness. So let me get this straight.
Black/yellow (switched) to "I"
to "L" (warning light)
to (ecu)
to (ecu)
Looking at the back of the alternator what terminal is "I", "L" and so on. Thanks

 

I'm missing something here. The car has run for 2+ years (I've owned it) with the green plug on the alternator missing (not plugged in). Is the alternator going at full charge rate all the time the engine is running? I thought there had to be the switched power to excite the voltage regulator to work? I need some help here - does anyone have what terminal is what on the alternator? "L", "I" etc. Thanks in advance.

 

http://ff-squad.com/wp/?p=425

Hope that helps.

 

I think I have the main players in the wiring figured out, I'm just having trouble at the alternator end. What terminal is which?

I I

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