I just installed an FD alt on my S4 TII as per a writeup I found on this forum.

The B terminal of the S4 -> B terminal FD
The L terminal of the S4 -> L teminal FD
The R terminal of the S4 = insulated and tucked
S terminal FD -> positive post on battery

One wirteup said to connect the "S" terminal of the FD alt to a constant 12V source (battery). Another said to hook it up to the EGI fuse (as there doesn't seem to be a readily apparent way too hook up to the EGI fuse, I went w/ the battery.

The problem is, the alt appears to be producing no voltage.
With the car off the battery reads 12.15V
With the car on the battery reads 12.16-.20 V

Touching the Alt post to the alt frame yeilds 11.56V
Touching the Alt frame to the (-) battery post yeids 0 V
Touching the Alt frame to the (+) battery post yeilds 11.56V

My voltmeter inside the car reads 10.5 V w/ the car on and 11.6 w/ the ignition on.

Whats going on here?

 

Alternator is bad or you left its belt off...humor.

https://www.rx7club.com/attachment.p...hmentid=199213

https://www.rx7club.com/forum/showth...ght=alternator

Although I like this one best: https://www.rx7club.com/attachment.p...6&d=1102811115

So, to be sure. pull the wire off the S terminal and with a meter check for batt voltage on that Wire. If it's there, then the alternator is bad. Note the S terminal is to the left of the keyway on the plug/jack. Get my drift when I say keyway?

 

Thanks for the links. I actually had copies of all those diagrams printed before I started this project.

In that first diagram it shows the S terminal from the FD alt connected to the EGI fuse, but there are no open terminals on or around the EGI fuse. I thought about splicing into one of the existing wires going to the EGI fuse, but that seemed like a bad idea, so I connected the S terminal directly to the (+) battery post.

I just checked to voltage on the S prong of the FD alt plug and got a reading of 0.00. (I got the same reading for the L terminal)

Actually I dont get what you mean by "left of the keyway" because when I pulled the plug out of the alt and looked at it, the S terminal is on the right side (w/ the locking mechanism on the top)

 

haha, I wish it were that simple. But sadly w/ electronics, it never is

 

Yeah. I call the locking mechanism the keyway.

And I was talking about how the WIRE in the plug should have batt voltage on it (S terminal).

Alt sounds cooked.

 

Damn, I guess thats what you get for waiting 8 months to install something you buy off the forum

 

That's my diagram, and splicing into the EGI fuse wire is what I intended it to mean. Dunno why you'd think that's a bad idea, IMO it's better than an unfused connection like you have. The diagram replicates exactly how the S5/S6 alternator is wired in stock form.

 

Thank you for clarifying that, it just seemed like it might be too much for that little wire to handle, that's all.

BTW I got the alt tested yesterday and it's good, so hopefully running it to the EGI fuse instead of the battery will fix the problem. If not, do you think the FD alt plug could be bad? would it be better to use spade connectors?

 

The current that wire is carrying is tiny, far less than the EGI circuit currently handles.

It's always better to use the correct plug rather than spades, but unless the connections are poor I can't see the plug being a problem.