Alternator charging by itself...?
Thread Starter
TECH Enthusiast
Joined: Nov 2016
Posts: 711
Likes: 6
From: PNW
Alternator charging by itself...? Finally completed my swap, filled it up with coolant for the first time to pressure test it and to find out which wire on the plug I needed to use to excite the alternator. Well as soon as I fired it up, the voltage jumped right up to 13.6v and stayed there - nothing connected to the plug. Using a 10ohm resistor I touched each pin to 12v+ to see if maybe it would do something but nope, it's charging all by itself. Are these self-exciting alternators? I was told they weren't. This is the factory alternator, 2006 GMC Sierra.
Thread Starter
TECH Enthusiast
Joined: Nov 2016
Posts: 711
Likes: 6
From: PNW
OK I found out this is the DR44 alternator and is self-exciting that defaults to 13.8v if nothing is connected to it. One pin is for the dash light, the other pin goes to a separate module that can control the voltage but isn't required for the alternator to function. Sounds like the ultimate OEM swap alternator, glad my engine came with this.
