Onstar backup battery replacement
CF Veteran
Joined: Mar 2011
Posts: 1,709
Likes: 4
Check with local service departments? The part lists for ~$93. Labor? It'll probably take longer to look up the procedure. See article OnStar Backup Battery - GM Techlink for how it may have happened.
CF Beginner
Joined: Jan 2010
Posts: 13
Likes: 0
From: Massachusetts
The Onstar unit is in the trunk, on the driver's side. Pull the trunk lining carpet away from the side of the trunk, and you will see it. The back-up battery is mounted on the side of the unit with a special bracket. Follow the instructions on the tech sheet listed above to avoid the check-engine light becoming lit. The battery is the "Ultralife" brand and has a GM part number of 88861186. Cost is 54.04 from www.gmpartsdirect.com. Follow the instructions in the GM tech sheet listed above and do it yourself. Save the labor cost. I hope this helped!! 
Administrator
Joined: Apr 2008
Posts: 7,573
Likes: 47
From: Austin, Texas
My 2¢, if you are paying for On-Star the least they could do is provide you the battery at no cost.....Call them and tell them the battery is bad so you are canceling your subscription.....
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CF Beginner
Joined: Mar 2011
Posts: 4
Likes: 0
From: Port Jervis NY
The Onstar unit is in the trunk, on the driver's side. Pull the trunk lining carpet away from the side of the trunk, and you will see it. The back-up battery is mounted on the side of the unit with a special bracket. Follow the instructions on the tech sheet listed above to avoid the check-engine light becoming lit. The battery is the "Ultralife" brand and has a GM part number of 88861186. Cost is 54.04 from www.gmpartsdirect.com. Follow the instructions in the GM tech sheet listed above and do it yourself. Save the labor cost. I hope this helped!!
Thread Starter
CF Beginner
Joined: Mar 2011
Posts: 4
Likes: 0
From: Port Jervis NY
Thanks Rods
Just received the BUB will install it soon. Thx again for the offer.<TABLE style="BORDER-TOP-WIDTH: 0px" class=tborder border=0 cellSpacing=1 cellPadding=6 width="100%" align=center><TBODY><TR title="Post 204418" vAlign=top><TD class=alt2 width=125 align=center>Lifted07</TD><TD class=alt1>2dogs Have you found a battery yet? If not I have one I removed from my vehicle. If its the same your welcome to it.</TD></TR></TBODY></TABLE><TABLE style="BORDER-TOP-WIDTH: 0px" class=tborder border=0 cellSpacing=1 cellPadding=6 width="100%" align=center><TBODY><TR title="Post 204418" vAlign=top><TD class=alt2 width=125 align=center>Lifted07</TD><TD class=alt1>2dogs Have you found a battery yet? If not I have one I removed from my vehicle. If its the same your welcome to it.</TD></TR></TBODY></TABLE>