I installed an entire new front suspension, Atomic's 4WD coilover kit and steering setup (idler arm, idler arm bracket and pitman arm) on my 05' Sierra last week. I am waiting on some last minute parts to arrive so I decided to start the truck since it's been down for a several days. I went to start it last night and nothing, other than the check engine light, lit up on the dash. No interior lighting, no locks, window controls, radio, dash controls, odometer, etc. Only the check engine light.
So, I figured the new, three month old, battery died since I did notice the interior roller switch was accidentally left on the other night. However I checked the headlights afterwards and they lit up, but somewhat dim. When I checked the headlights again tonight, nothing now.
I put the battery tender on it last night and am still getting the same results 24hrs later... nothing but the check engine light. I did happen to try the driver seat electric controls for the first time and they are getting power however extremely slow.
I put on a known charged battery box and the same results. I disconnected the negative cable for a few minutes and the same after reconnecting it. Nothing so far has changed anything.
I did a lot of web searching and surprisingly didn't come up with much. Thinking of doing a V.A.T.S. reset however I don't think that is the issue. It sounds as if the battery is toast but it is almost new, never given me an issue and the battery jump nor tender has changed anything.
Thoughts?

 

Sounds like the battery is no good. Same thing happened to my brothers truck. Left the lights on over night and killed the battery. Tried charging it like you did and same thing nothing seemed to work as if it fried the BCM or something. Just happened to try a different battery and it started right up no issues. Don't think lead acid batteries like to be drained all the way down. My brothers truck has a new battery as well.

 

So I hooked up my brothers battery via jumper cables from his SUV and everything on my end came back to life as it should. I put the tender back on my battery to see if she will take a charge again over the next several days. It's a AGM battery and new so I'm hoping for the best.
Thanks.

 

When batteries are depleted for any amount of time they develop deposits on the plates and basically decrease the effectiveness of the battery forever. Once you run it down once its greatly diminished. Deep cycle batteries are a little more forgiving about it but it still happens.

 

AGM's are even harder to revive after being totally discharged, especially if you don't have a proper AGM battery charger. One thing you can try if you have a regular charger is to hook a good lead-acid battery in parallel with the bad battery then put it on charge. Another is if you have a charger with selectable charging amps, put it on the highest setting to break thru the calcification of the plates. I have also had luck smacking small AGM batteries with a deadblow or on the concrete to break up the calcification which allowed them to take a charge.

 

The Battery Tender isn't meant to fully charge a dead (or even partially-dead) battery. They have a very low charge rate that is meant to maintain a battery to prevent it from going dead. You need to charge it with an actual battery charger.

Richard

 

BigKID is right.
I have brought Optimas back from the grave with the 2nd battery method. Just make sure the other battery is holding a good charge before you start. Then be patient and let it do its thing.

 

If the battery is new take it back to where you got it from and get a new one, most batteries have a 2-3 year free replacement!!