76 Alternator Upgrade To Maxima Alternator 90 Amps

[Datsunjoe76]

Hello guys, need a little advise and assistance with a recent alternator upgrade on my 280Z. I just swapped the OEM to the Maxima alternator and the pathfinder pulley eariler this week, swap and wiring went well until I realize that i'm loosing battery charge over night, battery goes from 12.24 after shutting down at night to 4.8V when tested the next morning. I've recently came across an older post on HybridZ that made mention of this being "Dead Battery Syndrome" and this may be in result of the "Brake Check Lamp Warning Relay"

 

Anyone has encountered such situation and can share how to resolve this issue? I appreciate the help!!

 

 

[NewZed]

You might be on the right track.  The relay is under the passenger seat. 

 

What wiring scheme did you use to get rid of the external voltage regulator?  There are at least two common ones.

 

 

[Datsunjoe76]

Hi NewZed I followed the direction from the link below to loop back the connector at the External Voltage Regulator, this was the only direction I could find to make this work. This was specific direction for the 76. Other year prior and after have different direction. 

Blue to White & Black

White to Yellow 

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

 

Thanks for your reply, I believe its your comment on the post I saw in regards to the relay under the seat. Trying to get the nightmare resolved. 

[NewZed]

I had the same problem.  My memory is vague but I think that I found that you could just disconnect the relay and the battery drain would stop.  But then the brake light in the dash does not work, for the parking brake or the pressure differential switch.  The brake light even acts as an "engine not running" light.  It needs power only when the engine is running, to turn the light off.

 

Anyway, I ended up cutting the power wire to the relay, I think it's the yellow one, and tapping in to the fuel pump power line, which is next to the passenger seat.  That restored the system to where it only had power when the engine was running.

 

That is the key.  The relay needs power when the engine is running only.

 

In the meantime I think that you can just unplug it.

 

 

[NewZed]

Here's another wiring scheme but I think that it causes the brake warning light to stop working.  Or stay on.  Can't remember.

 

http://www.zcarcreations.com/howto/voltreg.htm

 

p.s. if it's quiet when you're working on it you can hear the relay click and see a spark at the terminal when you reconnect the battery.  That tells you that you still have a problem.

Edited April 8, 2022 by NewZed

[Datsunjoe76]

Thanks NewZed I'll give your suggestions a try on Monday. I will let you know the outcome. Thanks 🙏  again. 

Have a great weekend.. 

[Datsunjoe76]

Quick update, problems solved due to some research and assistance from NewZed, power loss was due to relay below the passenger seat which ended up carrying constant power in lieu of switched power when the wire conversion was completed. Had to follow NewZed direction and connect this repay to a switched power source which I used the fuel pump power source. Hopefully this information can help someone else in the future. Thanks again NewZed for your advise.