Alternator wiring problem
 

Ok, If you read my other post you know that im working on an old turd 88 rx7 that hasnt ran in 7 years. Finally got spark (thanks to all you guys help!) and got the thing running. The alternator was removed 7 years ago, and I have to put it back on now. My problem is, The only wire the car has for the alternator is the big 12v lead. The other two wires are gone. There is a harness close to where the alternator sits that has two LITTLE chunks of wire sticking out that I think may have been the alt wires and got cut off for whatever reason.

My question is, what color are the alt wires, and which one goes on which terminal on the alternator?? Thanks a bunch!!

Here's a pic. It has both s4 and s5 as well as the fd alternator wiring setups. THey're all more or less the same except for the fact that one of the wires on the plug goes to the ignition on the s4...while the s5 and fd alts go to a 12v constant connection.

I believe that the one that goes to the dash is white, or grey or something, and the ignition wire is black. I could be wrong tho.

If all else fails just make some new wires!

Graat, thats just what i was lookin for! Thanks

The top wire on the alternator is BLACK/WHITE. It goes to a interior fuse. It's the ENGINE fuse. You get power to it when the key is to ON or better.

The bottom wire is WHITE/BLACK and goes to a relay inside the CPU. It provides a GROUND to that relay when the alt is not putting out. That in turn pulls the relay in and provides a 12vdc circuit to the ALT idiot light.

Thanks Hailers. Did you read the rest of my "NO SPARK! HELP!!" thread? It sure is wierd how it ended up working... Thanks alot for your help. You saved me months of trying to figure that problem out!!

i wired my alt up like the pic /hailers said, and its not working. Any way to troubleshoot it? Thanks

What makes you think it's not working? Because the volt gauge inside the car shows less than 12v?

What happens if you rev the engine up say to 3000? Does the alt then put out? It should even if the two small wires are not connected to the alt.

Pull the two wire plug off the alternator and see if you have 12v on the BLACK/WHITE wire with the key to ON. It should be there. If it's there, I don't understand why the alt does not put out.

Hi, The black/white wire has 12v with the ign. on. The reason I know its not charging is I hooked everything up, started the car.. The battery is getting low and showing about 10v. on the gauge. I revved the engine up, and it never went above 10v. So, I took the bolted on wire off the alt, and hooked up my volt meter and the large post on the alt was putting out nothing while the engine was running... Any ideas? Thanks

Shot alternator/alt diode assy. You did see battery voltage with your meter though, didn't you? Yes, but no output voltage from the alternator.

Hi, the black/white wire has 12v and the large output wire shows 12v. but with the large wire not on the lug on the alt, with the car running the lug shows no voltage. Do you think it could be a bad brush? I know the alt wasnt the problem why the car was parked. But the alt sat unused for 7 years and maybe a brush got stuck. Would it be worth taking apart, or should i just get a new alt? Thanks

I'd go the new/rebuilt alternator route. I THINK internal parts are difficult co come by.

Okie doke... I will start looking for a good used or new alt. Thanks hailers.