2017 Toyota Sienna Automatic (85000 miles) with a good battery (battery replaced 3 times) will not always start. Jumper the battery, it will start and be trouble free for months. Then randomly it will not start. No codes. Dealer can't fix it because it is too random!
have your alternator load tested
Does the van not start because the battery is dead? If the alternator tests good and there's no battery light lit up on the dash, then I would suspect a parasitic power draw issue that's draining the battery.
There's lots of great videos on how to diagnose parasitic draw at the fuse box using a multimeter.
@oskool Thanks. My brother gave similar information. I will do some research. Thanks again.
I would also check the starter...although Toyota starters normally last longer than 8 years...
