I'm wiring my 88 Camaro from scratch, using the stock 4-wire alternator. The main power wire goes directly to the battery, the smaller red wire on the plug, also to the battery. The brown wire, post "L", is not hooked up because I no longer have a voltmeter. The tan and white wire, post "F" is what I believe is giving me the problems. From what I've read, the tan/white wire needs to show the alternator 0.5 Volts less than the battery while the car is running. Battery is 12.6 volts across the terminals when not running. Battery jumps to 14.5 volts when running. When I disconnect the battery, the car dies, so obviously I'm not getting a charge out of the alternator. I've read in posts to wire a 27.5 ohm or 33 ohm resistor into the tan/white wire to step the voltage down 0.5 volts in order to get the regulator to make the alternator start charging. Does anyone know the amperage draw of the tan/white wire? Using Ohm's law, with 27.5 and 33 ohm resistors, and a difference in voltage of 0.5 volts, the amperage draw appears to be 0.018A and 0.015A, respectively. If I knew off hand the amperage draw, then I would be able to select the proper resistor to produce a voltage drop of 0.5 volts.

 

umm, disconnecting the alt while it is running is a very good way to kill the alt.


if you are getting anything higher than batt voltage with it running, it is charging


btw, 14.5v is perfect for a good alt

 

I've never disconnected the alternator while the car was running. The motor was either running with the alternator disconnected, or with it connected. On the alternator, with the plug connected and the main power wire disconnected, I'm getting half a volt at best at the main power post on the back of the alternator. When I connect everything up, I get 12.6 volts across the battery terminals when the motor is not running, and 14.5 volts when it is running. When I disconnect the negative battery cable, the motor shuts down. What gives?

 

NEVER disconnect the batt with the engine running, good way to fry the rectifier

it is charging now, why are you messing with it?

oh, and you will not get anything out the back post of the alt if it is not hooked to 12v