Intermittent Lane Light Problems Solved with Better Battery, even when generator working!?

I doubt it would throw up random error codes because the ECU can run with as low as 9 volts, and below that it will shut off, but above that it works fine. If it is giving errors about sensor drive voltage then it could be a voltage issue but the computer won't glitch that way if it has low voltage.

I've had experience in auto applications where the first indication the battery is starting to go bad is the electronics start throwing off errors and just acting weird.  One might assume an ECU will just quit below a certain voltage, but it may well become erratic before it actually shuts down completely.

Tyler Hathaway wrote:

I've had experience in auto applications where the first indication the battery is starting to go bad is the electronics start throwing off errors and just acting weird.  One might assume an ECU will just quit below a certain voltage, but it may well become erratic before it actually shuts down completely.

It complies with RTCA/DO-160 section 16.0 so it has to handle power variations.

So it has to be able to "handle" various voltages, but what does that really imply?  That it will work perfectly until it stops working completely?

Yes it will work according to spec until a certain voltage and then it will shut down or go into some kind of brownout protection mode. This can be done with a diode that is an insulator below a certain voltage and a conductor above that voltage.

It is better for it to stop working completely instead of stop working partially because a malfunctioning ECU can destroy an engine. And when it stops working completely because of low voltage then the resistive load on the generator or battery goes down, which means the voltage goes back up (ohm's law) until it reaches 9v and the system can start up again.

That's just the computer part so I don't know if other components of the engine can malfunction at lower voltage that could be causing the sporadic errors. Maybe the voltage is not so low that the ECU shuts down but is too low to drive the ignition coils and that's why there's an ignition coil error? I don't know about that. Unless the ECU is either off or reporting "low ECU voltage" faults, then the voltage is at least 9 and the ECU is working as it should.