I wired in an S5 alternator per the tech articale. Green/White wire to 12v battery, black/white wire to the original black/white wire that goes to the choke/check relay.

Now key on engine off, dummy lights aren't lit. Key on engine on, dummy lights are lit as soon as the alternator comes on. It's like the black/white works backwards?

Anyone else have this problem?

 

 

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/frequently-asked-questions-2nd-generation-rx-7-faq-fc-494667/
scrool down for wiring diagram...

 

That's exactly how I have it wired.

 

Are you sure? you mention the black/white wire on your original post. The wire you want is white with a black stripe (like what wacky is showing). Double check to be sure.

If everything is wired correctly and the problem is still there, you may have a dud alternator. When the engine is running, what is the voltmeter reading?

Possibilities:
- wired wrong
- defective alternator
- broken/missing alternator belt
- bad choke&check relay

Is the alt used or new?

 

Bought used from a member with good feedback. Volt gauge reads about 13. Been fighting a voltage drop with the ign switch circuit. 14v at battery. No dummy light problem before alt swap though. Yes, wired the white with black stripe. Not the key on power black with white stripe.


Only other thing I did was remove the rats nest pigtails that were just sitting there.

 

I put an alt out of a 93 Buick in my 7(105amp) and im having the same problem. I wired it right and i even swapped the choke check relay with another and it still does it. i think it might just be supplying too much power and have to put an external regulator on it. they only do it intermittently though

 

Sounds like it is charging. To check the choke&check, you could simply unplug the WB wire and see what happens with the warning lights. Then you can ground the WB wire (the side that goes to the car) and see what the warning lights do. If everything is okay, they will be on in one case and off in the other.

If the alt and/or waterpump has been painted, make sure to clean off the paint at the mounting ears so that the alt can get a good ground.

For the 1v low reading in the car, mine does that too and I have see lots of other 1st gens do the same. I imagine it is more a calibration issue than anything.

 

No painting of those items.

Did some electrical checking tonight:

KOEO:
WB wire unplugged, dummy lights off
WB wire grounded, choke and check relay clicks, dummy lights on
Alternator L terminal no power, no ground

KOER:
Alternator L terminal is grounding.


So basically the L terminal is functioning backwards? Should ground all the time then un ground or provide power when the alternator is charging?

 

The pictures that wackyracer posted show a different alternator than the one I came up with.

I did a little research and it looks like I've got the Turbo S5 alternator. Does the WB wire have a different function on turbo cars?

 

Nothing should be grounded 1 wire to b terminal and the other to pig tail tii alt are the same except for higher pipit iirc

 

Must mean the alternator is bad. I'll yank it off and have my parts guys check it. Maybe they can figure out the operation of the WB wire.

It definitely grounds when the alt is charging. I fired it up without the WB wire. Used a test light and it turns on connected to 12v.

 

What action am I supposed to have on that wire?

Is it supposed to ground key on, (turns the dummys like on in check)

then break connection, or provide power when the alternator is charging?

 

I came across my pix of my other installs. here ya go

 

13V out is pretty low, isn't it? Don't most charging circuits run about 13.8-14.4 lightly loaded?

 

Sure is. I think mazda low balled the wiring into the dash. I've got a strong 14v out of the alternator but at the ignition switch it's less. The switches are pretty chinsey in my opinion. Riveted leads that swivel brand new. Can't be good for carrying voltage. Plus just about everything dims when anything happens... Turn signals, brakes, etc.

I've replaced both battery cables with high quality welding cable, and have a killer grounding system. Still hasn't helped. I'm thinking about tearing the whole harness apart and running a larger gauge power wire to the switch.

 

install an aftermarket volt meter instead for a second opinion