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Delco 10SI alternator issues

6K views 8 replies 3 participants last post by  EOD Guy 
#1 ·
I've been messing around with my alternator and getting frustrated. It's set up as a 2 wire right now. I had the 3 wire (using an idiot light) but when the key was turned on, the light didn't come on. The bulb was good because when I grounded the end that connects to #1 terminal, the bulb came on. My other problem is I have to rev the engine well over 3K rpm to "excite" the alternator. Regardless of what I do (changing pulley's etc) I still have to rev the heck out of the engine to excite the alternator. The alternator is chromed so I'm wondering if it's a ground issue? voltage regulator/ diode issue? Just looking for possible solutions or if anyone else has been there.
 
#2 ·
Sounds like the bulb is the incorrect one for starters.
The real issue may be the lack of a drop resisitor that was famous in the 10SI when it was assigned to do 63 amp duty. It is a drop resisitor that bridges across the regulator inside the alternator, to excite the alternator at low rpms, to remedy the xact type of problem you are having.
You do have power on the # 2 terminal with the key on...correct?
 
#3 ·
I've disconnected the bulb completely. The #2 terminal has a jumper running to the Battery post on the rear of the alternator. The other is a 4 GA wire running from the Batt post of the alternator to the + side of the battery. So, if I replace the regulator, will this solve my low rpm excite issues?
 
#6 ·
I appreciate the info. I was messing with the alternator again tonight and decide to use a different idiot light. I turned the key on, nothing! instead of using the original connection on the alternator, I ran a separate wire for terminal #2 and 1. #1 being for the light. When I put the connection onto the prong for #1, the light came on. If I wiggled the connector for #1 slightly, the light would come on and off as I wiggled the terminal. I tried to start the car while the light came on and I revv'ed it to about 2K and the alternator excited! (so did I). I'm not sure what the problem is, but something is not right with terminal #1, so I may opt to purchase a new voltage regulator and see if that solves the problem. Getting close! Thanks for the help.
 
#8 ·
I had mine hooked up the same way. In this case, with the light, the light let me know terminal #1 is not making a connection somehow. If I ran it straight from a switched 12V, I would still assume #1 is working fine. It's weird, #1 is not loose but if I push against it slightly, the light works, when I let go, the light is off. Don't know what caused this??? Once I fix this issue, I'll go back to no light like EOD Guy and a resister in the line only.
 
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