2020 Sierra 1500 dead battery

snyderfarms · July 29, 2020

On two separate occasions the battery has went completely flat on the truck. Charges up and then is fine. Both times the truck has been started moved a short distance and then parked for the night dead the next morning. Both times coincidentally have been towards the end of the month when the onstar diagnostic email comes out. Any ideas?

Steve-2019 · July 29, 2020

Do a search on here, there are lots of others that have posted about this issue.

snyderfarms · July 29, 2020

Tried. Scrolled through the results for 45 minutes. Thanks

steve841 · July 30, 2020

The bulletin floating around says to tighten the fuse box mounts in the engine bay (with green pop ups).

No issues for me, but I checked anyhow. Mine were fine. While I was in there, I tightened up the battery terminals - which needed some love.

snyderfarms · July 30, 2020

1 hour ago, steve841 said:

The bulletin floating around says to tighten the fuse box mounts in the engine bay (with green pop ups).

No issues for me, but I checked anyhow. Mine were fine. While I was in there, I tightened up the battery terminals - which needed some love.

Ok I’ll check that out. Thanks

Gangly · July 30, 2020

Mine experienced the same problems that yours is, and the answer I received was that it came from the factory with a "bad cell" according to a technician. They replaced the battery and I've had no issues since.

Something else that I noticed is if I accidentally leave my keys in the truck over night, the battery is sometimes weak in the morning.

snyderfarms · July 30, 2020

3 hours ago, Gangly said:

Mine experienced the same problems that yours is, and the answer I received was that it came from the factory with a "bad cell" according to a technician. They replaced the battery and I've had no issues since.

Something else that I noticed is if I accidentally leave my keys in the truck over night, the battery is sometimes weak in the morning.

They’ve tested my battery load tests fine so they won’t replace it. I leave the fob in mine every night. The thing I don’t understand is it’s set for a weekend and had no trouble but I’ve moved it 15 feet on two occasions and been completely flat the next morning.