Hey guys, I just discovered that one of the previous owners swapped out the alternator for the 60 amp 280zx alternator. I read the atlantic z car write up on how to wire it, and whoever wired this did it completely different. They connected wires 5 and 6. The car runs but the voltage drops when lights are on, heater is on, flashers are on or the radio is on. I also noticed the brake warning lamp relay under the passenger seat is disconnected because it the brake lamp stays on permanently when its plugged in. Does having that relay unplugged have a negative affect on anything else and how is the car running with only wires 5 and 6 connected?

http://atlanticz.ca/zclub/techtips/alternatorswap/index.html

The only thing the brake relay will do is turn the brake warning lamp on as part of a "lamp test". Having it unplugged will have no negative effect on anything else.

I don't know anything about the alternator upgrade.

Wow! I have the same situation! I just removed the brake bulb because it bugged me, but my regulation system is the same as yours. We should compare notes.

Post #4 here talks a little bit about the light - http://www.classiczcars.com/forums/thread36480.html

Ok so I rewired the alternator according to the atlantic z car write up, the charge light and brake warning lamp test now work just fine, but for some reason now my idle is always too high, like 1500 rpm, I dont think this should be related to my re wiring the alternator but none the less its happening, and if i adjust the idle down with the idle screw, after the car cools off the idle is now way too low, any ideas?