Hi all. I am new to this forum but I can not figure out how to make a new thread. (I think I just managed to do so) 2003 blazer 4.3. I done some tests. Before I try a new alternator I wanted to check on this finding. With key in run position, I found only 10 volts on that brown wire which plugs into the alternator. Presently the alternator is charging at only 10 volts as shown on the dash gauge and voltmeter. The idiot light in the dash with the battery symbol will flash when the battery is so low the car will not start. I know because I ran the engine about 20 minutes. I turned the ign off, and the light flashed and the car would not start.

I know the alternator will not charge if the brown wire does not have current. How much should it have. I assume it should show the battery charge. What would cause it to read only 10. Where should I look first? It is of course inside the wire wrap. Where does it go next? Perhaps there is a dirty termination I could clean. Perhaps a junction box? The car is new to me. I was told the engine was hosed down often.

Before I throw a new alternator in, remove and return, and re-install old. I thought I might ask about this.

​​​​​​​Thank you

 

Most parts stores will be able to test your alt. Take it off and have it tested

 

Thank You,

I took it of an bought another. Works now. For anyone else in the same situation. That feed wire for the alternator only produces about 10 volts when on ign. The voltage must be controlled by a computer and the field not energized until on run. That is all I can surmise, since all I got was 10 volts, but everything works with new alternator.