Onstar Battery?

[stuffs2936]

I have a 2004 Yukon. When I purchased it (used) they upgraded the onstar to digital.

I just discovered (the unfortunate way, lol) that with the keys out of the ignition Onstar could not unlock my truck.

Furthermore I realized that the blue Onstar button will not connect me when the ignition is off.

If the truck is running everything is working.

I am wondering if there is a backup battery for Onstar that might have failed.

Does anyone know and where would I begin to find the battery and unit?

My Alldata subscription does not seem to cover Onstar.

The Dealer wants a huge diagnostic fee and if the box has failed I think it a fortune.

 

Any help will be greatly appreciated and I thank all of you in advance.

 

John

[SouthCo]

I don't think Onstar has a seperate battery. Possibly when the upgrade to digital was done it wasn't wired correctly (perhaps wired to switch instead of constant hot)?

[stuffs2936]

I don't think Onstar has a seperate battery. Possibly when the upgrade to digital was done it wasn't wired correctly (perhaps wired to switch instead of constant hot)?

 

 

Thanks for the reply!! I thought that also, but when I first turn off the key and remove it , onstar works for a a couple of minutes and then is dead. It is difficult to get info from them but one guy at Onstar seemed to think there was a backup battery so Onstar would function in an emergency even if the car battery was dead. I am thinking it might be as simple as a small lithium battery as used in computers. The big problem is where is the unit and how to get to it.