Hi so I’m having issues with my 63 c10. The alternator will not kick in and as a result I had a flat battery the other day after a nighttime drive. I have bought a new 3 wire gm si series alternator. I’ve wired it correctly the same as my old one which ran for years like it . Pin 1 is to exciter pin 2 12v bat and then that goes to the power output on the back with a bat cable that goes to the starter. if I remove the bat cable whilst running the engine the generator emits power but when I put it back on to supply the truck it dips off as if its straining under load but I believe still running as it should. But I only see 12v at the battery. did some digging and the exciter wire when ignition is off is constant 12v live and it’s travelling down that wire from the alternator to the fuse board and into the accessory loom so powering my radio etc with ignition off ?! If I unplug the exciter wire under dash radio goes out and then will work as it should when you turn on ignition. So my question is should I have 12 v coming from the exciter on the alternator when it’s not running ? I don’t think that’s right and why would it happen? And I also read that the exciter needs over 12v to excite the alternator is that true ?