I need some help, this has got me stumped. I have a 65 V8 coupe and my battery is not charging. I am getting 11.5-12 V across the battery with the engine running, from what I have found out, it is supposed to be 13.5-14 V. I have had the battery and alternator tested and they are OK. I have replaced the regulator twice. When I bypass the regulator (if I am doing it correctly, across the 2 center posts on the plug) I get 15 V. I have checked the continuity on the 3 wires going from the regulator (white and black, yellow, and black and red) I think they are OK. I don't know what else to check. Does anyone have any ideas?

 

First thing I'd do is recheck the continuity while referring to the wiring diagram.

1965 Mustang wiring diagram

All the wiring diagrams are in the FAQs.

 

well for what its worth i had a similar problem. id wiggle the wires going from the regulator towards the dash and the voltage would increase. i finally found where there was a bad wire and put a new one, solved the problem. also found a bad ground wire going from the back of the engine to the firewall. seems your on the right track by jumping the regulator and getting it to charge. seems the wire that suppose to switch the regulator on is bad. worse case is you could go with a one wire alternator.

 

Bypassing the regulator with a "full field" test will cause the alternator to produce full power. Don't do this at idle, do it at 2000 rpm.

 

ya. not at idle. further check if your engine and chassis is grounded. mayeb you pull ground from sowhere where you don't have any