Intermittent Auto Stop
 

Recently bought a 2016 Impala LS, 40,000 miles. The auto stop/start function worked fine until about a month ago, now it seems to have a mind of its own. It works intermittently, one day it will work then won't work for several days or more, then work again. Called the dealer but they want $120 just to troubleshoot, another dealer wanted to do a battery charge/test taking anywhere from 1-1.5 hrs. I checked the voltage of the aux battery in the trunk with engine off and it was 12.78 after sitting overnight. Any suggestions? As a sidenote I know GM did this to meet fuel mileage requirements and I feel it really doesn't save any gas, and may increase wear and tear on the car with all the stopping and starting. Maybe just live with it????? Thanks

there probably are numerous inhibit criteria that would cause the system not to function...battery state of health is the main one. the batteries must be isolated and tested individually.


if you disconnect the battery sensor...the system may take a couple days to learn the battery state of health.

not sure about your build but most new stop start systems use the alternator and a special belt tensioner set up to start the car for stop start restarts so as not to wear the conventional starter. the conventional starter is used for cold starts