junito1

If you only connect terminal B to the battery and nothing else, should I see battery voltage coming out of terminal S? I was under the impression S received voltage so why does my alternator put out voltage... and what does it mean

DaBrkddy

Where are you connecting the test leads of your VOM, and under what conditions are you connecting them?

junito1

Pulled the 2 wire plug out(S & L). Only left B connected to battery while car is shut off. Test leads went on B at the alternator and ground was a bracket in engine bay. It read 12.xx volts.
Then I moved my lead to the S at the alternator and it also show same 12.xx voltage.

Why does S give and receive voltage... is this normal circuit for alternator.

DaBrkddy

When you test "S" where is your other lead connected?
S4 manual for reference, others similar:

junito1

I don't follow..
The test meter leads? I don't know what you mean. Positive on S at the alternator. And ground on any ground near by the alternator...

DaBrkddy

Yeah, based on that it sounds to me like you might have at least one bad diode inside the alternator. Any auto parts store with an alternator tester can verify this.

junito1

BTW my car is s4 with chassis harness has been simplified by eliminating all wire to u used accessories such as ac,radio,idiot cluster,etc. The car has has an FD alternator wired same as shown on 1st post.

I started getting worried ,probably for no reason, when I removed the fuse out of the signal wire to S. When I tested the pin on battery side of fuse holder it read 12v when I tested the other side which I expected zero- it read 3.xx volts .... which means S is giving out 3 volts. I then proceeded to test S at the alternator with 2 wire plug removed- it read 12v.

Yeah IDK... I need to try this again see if it duplicates.

junito1

Also what happens if S doesnt receive battery voltage 24/7. I read a few threads and HAILERS seemed adamant bout S being connected to constant 24/7.
Anyway I realized I had it after the kill switch which mean it is not connected anytime it's parked... what can this cause...

DaBrkddy

"S" should only recive battery +12 voltage when the car is on and running. If it has +12 volts going to it when the car is off I would think this could at the very least drain the battery.

DaBrkddy

This might help.

https://youtu.be/tiKH48EMgKE