Hi everyone I am new to this site. I have a problem with an alternator. I currently have a 1973 FJ40 and have completly removed all of the wireing and harness due to an elecrtical fire by the previous owner. I have rerun all of the ignitions wires and got it so it will start and run just fine except for the charging system. Due to the factory alternator not working due to age and wireing harness gone. I made a bracket and put in a so called single wire alternator (NAPA # 213-4011) to make the wireing simple. The problem I am having is that the alternator only charges when I rev up the engine to I think around 800-1000 RPM's. When at idle the engine is running from the battery and not charging. There is a black plug on the bakc of the alternator that I think has a two prong plug in it. My question is can I run a wire from the ignition switch to one of the those terminals to stimulate the alternator at idel to charge the battery. Any help would be great. Thanks in advance.

For a side note this FJ40 sat in back field for the last twenty years and has extensive rust and damge to the body. I am fixing it up slowly and the other dat I took it for a drive...just with no brakes or seats yet.