Hey Scotty, I watched your latest video My Lexus Finally Broken Down and I’m Mad as Hell and it got me wondering: Does disconnecting the negative battery terminal reset the ECU or computers? Let's say I need to change the alternator but I don't want to reset the computers - is it possible?
Unhooking the battery does reset some things.
Use a car battery memory saver (web search for that).
Thanks! I never knew about this device until now.
Chances are you discovered the bad alternator when you car would not start so your battery went dead anyway making the question moot. In general the computer retains all the vital setting when the battery is disconnected. Depending on the length of the power interruption the computer may go through a re-calibration where it re-checks all the systems and sensors but if all is well after a couple of drive cycles it will be fine. Typically you don't even notice unless you have a scan tool hooked up. The scan tool will indicate "pending" on some parameters until they are rechecked during driving.
