My power locks stop working except on hatch, myCruise info and climate settings wouldn't show on dash screen.this would last anywhere from a few days to a week.eventually I would try to start car.

Insufficient chassis ground...the main ground connection....1/0 battery cable from the battery (clamp side) connects to the frame (lug end)...undo the lug and hold the lug with a pliers and wirebrush the lug free of any corrosion...and also the chassis where the lug bolts to...to establish a solid 300 cold cranking amp connection and steady milliAMP needs for the delicate components which are fussy about the voltage....a heated 02 sensor being able to take it's readings correctly is a prime example....REFRESH the ground...with your NEW battery....as five is too old to accept a charge properly and leaves you with a compromised battery with voltages that will throw up CEL lights and computer will not be deciding critical decisions such as temperature=richness of fuel mix~

1999=dead as a turnip...surprised it worked at all anymore~