Delco 12si signal wire question.

[JohnnyB]

Hey guys, I just installed a 12si in my 67 dart. I've got everything hooked up and working correctly but I have a question about the signal wire. I ran a 6g lead to the starter (then I have a 1/0 to the bat from there). I hooked up the original charge wire (the one that runs through the ammeter) to the alt output as well. I have the signal wire run straight to the output stud on the alt but I have read that it is better to take it from a source closer to the bat.

So, after looking at the wiring diagrams it looks like I can use the original charge wire as a signal wire to the alt as it runs down to the hot side of the starter relay on the other end. Am I correct? Will this work, or will it let the smoke out of the ammeter?

Thanks

 

[67Dart273]

Here's what you need for 12SI. The plug is NO1 and NO2

No2 is the "voltage sense" and this has very little current. It needs to accurately sense battery voltage, and connecting it to the alternator stud is OK IF the charge wire is nice and big. (No8 or no6 direct to battery) Otherwise, you want a dedicated wire from it to "as close to" the battery as you can get, IE the starter relay

No1 is the "excite" terminal and this used to go to the idiot light. DO NOT hook this direct, as eventually you will pop the diode trio. Either wire it through a lamp and resistor as GM did, or you can ALSO use a series diode

This photo shows the no2 hooked to the stud, but the important thing is the series diode needs to have the band end towards the alternator If you have a "one wire" you can ignore the no1 connection

 

[JohnnyB]

No1 is the "excite" terminal and this used to go to the idiot light. DO NOT hook this direct, as eventually you will pop the diode trio. Either wire it through a lamp and resistor as GM did, or you can ALSO use a series diode

I guess I failed to mention that I hooked it through an indicator light to a hot-in-run power source.

This photo shows the no2 hooked to the stud, but the important thing is the series diode needs to have the band end towards the alternator If you have a "one wire" you can ignore the no1 connection

The photo is almost exactly how I have it installed. The only difference is that I have a light instead of a diode and I ran an additional 6g to the bat.

No2 is the "voltage sense" and this has very little current. It needs to accurately sense battery voltage, and connecting it to the alternator stud is OK IF the charge wire is nice and big. (No8 or no6 direct to battery) Otherwise, you want a dedicated wire from it to "as close to" the battery as you can get, IE the starter relay

That's where my question lies. Since the ammeter is connected to the starter relay, can I use it as the signal wire? I know that the ammeter won't be reading correctly, but I want to know if it will affect the voltage the alt sees or will it damage the ammeter (or anything else)?