Hey guys, I believe I have stumbled across the ECU bypass for the alternator charging system by accident.

I have a voltmeter hooked up to my cigarette lighter port, and noticed it would shift from 12v to 14v sporadically. After hours of research, I found there's a smart system that cuts the alternator on and off when demands are high or low to extend the life of the alternator. For many of us running an aftermarket audio system, we're struggling with the undersized alternator output and can't afford for the charging system to decide "low demand" and drop our alternator output randomly.

On your factory battery negative post, there is a small black battery sensor with a 3 wire connector. If you disconnect this and start the car, you will get an error code "Check Charge System"..... BUT you will be at a constant 14+ Volts! You can also pull the fuse for your battery sensor but it will also cut your DRL (daytime running lights) in the Gen. 3. It is either fuse #15 or #17, both 7.5 amp fuses.

I have been running my Fit this way for 6+ weeks with no issues yet. I purchased a shunt and an ammeter to read my amperage draw on my charging system with the battery sensor connected vs. disconnected. I'll post results when I set everything up.

I will also be upgrading my alternator to a 280 amp output in the upcoming weeks. I'll post a new thread once it's complete hoping the ECU bypass allows me to pull more than 100 amps LOL.