My 09 H2 battery went dead twice when the truck sat for 2 days or more. I have read here that pulling the OnStar fuse might fix the problem but to no avail I could not find it in the 09 fuse box, labelled info. I took the truck to a performance shop near me and had them check the stock battery.It showed less than 50% cranking amps left in the batt after the 25 min drive there.So,battery NFG.I told the shop guy to put a Optimia battery in her since its a dam good battery. He put one in and had the batt *** backwards,pos where neg was on the gm. bat and neg where pos was. In short, reversed from where gm posts are. Soon as he hooked up both cables the horn came on,3 times he did that with the horn honking, then he realised he put the optima in backwards.He reversed the battery, hooked up the cables and she fired up fine.When I left the shop a little ways down the road a red battery icon came on and my volts on the gauge were down to 9 v.No battery icon before and 14 v was on the guage before putting in the optima. Since I was closer to home I took out the optima and put the gm bat back in and went to the gm dealer by me.I never told him about the batt swap and battery in backwards. Their shop ran tests and the pos cable from batt to alt is shot,200 amp fuse blown in it.And other fuses in fuse box to. No radio, backup camera, even the turn signals don't make the blinking noise when you turn them on, they do blink though. Dealer also said alternator might be shot,wont know till more tests done.Anyway,all that from hooking up the cables in reverse. If alt is shot my extended warranty should cover it but not for all the fuses and pos cable with 200 amp fuse. The cable has to be ordered from the states,Mon or tues next week before they get it.Anyway,just want to let everyone know what kind of damage you can do by hooking up a battery backwards. The performance shop said they will look after me and I have been dealing with them for over 10 years.. Has anyone ever done this. And what damage can be done on top of what the gm dealer told me.Any info appreciated.Gotta go open up a bottle of crown royal and drown my troubles away. Chow.

 

On page 5-111 of the 2009 H2 owners manual it says that the onstar fuse circuit is labeled "onstar" and not "info" like the earlier models have. Also, the fuse is located in the INSTRUMENT PANEL fuse block, second row of fuses from the right, second one up from the bottom.