Resistor, Diode or Both

[BJSZED]

Looking for wisdom on whether I need a resistor, diode or both on my alternator upgrade ? I know I need the diode to prevent run on after the ignition switch is turned off but am unsure of the reason for the resistor ? 

 

- 1972 240z

- 90 amp maxima alternator

- new speedhut voltmeter which does not use a light ( for the resistance on the ignition circuit ) 

- new wiring, old voltage regulator is gone 

 

thanks for your input !

Edited May 24, 2018 by BJSZED

[NewZed]

4 hours ago, BJSZED said:

 I know I need the diode to prevent run on after the ignition switch is turned off but am unsure of the reason for the resistor ? 

 

Where did you get the thought that you need a resistor?

[BJSZED]

I've been reading on-line and getting confused. I think the resistor comes into play on a 4 wire alternator. It is used instead of an alternator charge light. Without it apparently it won't charge at idle.

I believe I just need the diode on the run/start ignition wire from the ignition switch to the alternator.

[NewZed]

The diode goes on the L wire.  Are you sure the Speedhut meter doesn't have a charge warning light?  

 

Either way, you should be able to use the typical 240Z alt swap wiring instructions.  But, it's actually pretty simple.  Study what the S and L wires actually do, and just wire according to function.

[NewZed]

Do the swaps one at a time also or you might not know which swap is causing problem, voltmeter or alternator.

[BJSZED]

Thanks for your responses...good advice, will do