Mysterious power failure
 

A few day ago I posted a power failure issue I had with my 2012 370Z. The problem was, there was no voltage going to any part of the car, with two exceptions. The brake lights worked and the windows dropped slightly when the door was opened manually. The Intellikey didn't work. There were no status lights on in the instrument panel, no interior lights, no flashers, nothing. The car was dead!

The battery cables were tight when I checked them and the battery was fully charged. In a desperate attempt to try something, I removed the ground cable then re-connected it. The horn alarm sounded, everything else came back on-line and the Intellikey worked again... but why?

I talked about this with at least five service reps at my Nissan dealer. Not one of them would even hazard a guess as to what the problem might have been. I mean they shrugged their shoulders and just clammed up. Man, talk about feeling abandoned. How difficult would it have been for one of these experts to do a little analytical head work for me? Even I know the first suspect would be the battery and cables. Then comes the voltage regulator and so on down the line. I mean how many parts are there in a car that can cut off all power?

I was very disappointed with Nissan for leaving me to figure this out on my own. They could have been much more helpful, but weren't. I'm happy everything is working now, and I hope this doesn't happen again while I'm driving. Hope it doesn't happen to anyone else.

Can anyone in this forum offer me more in-depth help or advice? My car and I would be grateful.

My guess is that you didn't fully discharge the system (there are capacitors in the ECM that can hold a charge) the first time you disconnected the battery. If you have to do it again, press on the brake pedal for a few seconds after disconnecting the battery cable.

Edit: The root cause was probably a glitch in one of the control modules. Killing power reset the module.

I had something similar happen, twice! Came out in the morning and the car wouldn't start as if the battery was discharged. Voltmeter reads like 9-10V. Gave the car a boost and let it run for five minutes. Shut down and then restarts like nothing had happened. Voltmeter reading while running was above 13V and gradually got back to normal of ~14.5V after a few hours of driving. Happened again after a few months for no apparent reason like the first time. Gave it a boost and all was fine except the low voltage reading. Never did find out what wrong. Car had less than 6000 miles on it when it happened the second time.