OnStar Back Up Battery Issue #PIC4541E Diagnostic Tip- OnStar Back-up Battery Failure

[texn884]

Hi everyone,

Yesterday after starting in the Rat in Ruidoso, NM and then stopping and then the check engine light came on and the light on the rear view mirror on the far right started blinking red and I thought WTF now!

I called Onstar and they said the check engine was a loose fuel cap and the blinking red light was a low battery in the OnStar module Its #PIC4541E its for 2009 G8's is what the local GM store printed out for me.

I was wondering if you can take that module out of the trunk and replace the Battery myself or they sounded like I might need a whole new one!

Any ideas?

[JonRobbinSS]

I believe the battery is actually above the hat-shelf inside the car (under the rear deck carpet). It is separate from the on-star module. It is a onetime use only battery, meant to be used in a collision. But if the main battery is disconnected improperly it will start the clock on the battery..

on-star%u00252Bbattery.jpg

Recommendation/Instructions:

Do not disconnect the main vehicle battery or remove the OnStar® fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be disabled (simply opening the drivers door should disable RAP) before disconnecting power.

Disconnecting power to the OnStar® module in any way while the ignition is ON or with RAP activated may cause activation of the OnStar® Back-Up Battery (BUB) system and will discharge and permanently damage the back-up battery. This action is per design as the BUB is designed to provide power to the VCIM so an emergency notification call can be made after a vehicle collision where the main battery is disabled.

Once the Back-Up Battery is activated it will stay on until it has completely discharged. The BUB is not rechargeable and once activated the BUB must be replaced.

Important: Do not remove power from the OnStar® VCIM with the key on or with RAP activated.

[texn884]

I changed the stock battery a few years back pretty straight forward remove and install

[texn884]

That picture you posted where is that in the car?

I believe the battery is actually above the hat-shelf inside the car (under the rear deck carpet). It is separate from the on-star module. It is a onetime use only battery, meant to be used in a collision. But if the main battery is disconnected improperly it will start the clock on the battery..

on-star%u00252Bbattery.jpg

[LDM]

It's the shelf behind the rear seat. Here's another view of the battery.

[v84me]

I yanked the XM and Onstar years ago, but didn't know the back up battery was separate. Guess I might as well pull that out as well. Thanks for the picture.

[THE Adam V]

Mine is dead as well. But my car was under the knife for 8 months. Interested to see if you can fix it yourself or not.

[texn884]

From what I have been told you have to take the Rear seat and shelf out and you can replace the fucking battery and it runs about 50-100 bucks. Once you take stuff apart like that you can never get it back together right IMHO, the bastards.

I guess that is why my battery sounds a little weak when it sits for a while.

[-Ray-]

From what I have been told you have to take the Rear seat and shelf out and you can replace the fucking battery and it runs about 50-100 bucks. Once you take stuff apart like that you can never get it back together right IMHO, the bastards.

I guess that is why my battery sounds a little weak when it sits for a while.

If you take the onstar box out, you don't need a new battery.

[texn884]

Is the Onstar Box the second one in the trunk or is that the radio amp? There is a XM box and a second one on the underside of the trunk on the drivers side