I have a 2007 GP GXP and recently my light has gone red. If I go from accessory to run on the ignition the light goes green for a few seconds then back to red. Onstar did a diagnosis and said there was an antenna issue, so I replaced the antenna, antenna mount, and amplifier. Since then no issues detected from onstar, but still have the same redlight problem. Please can someone tell me where the backup battery is.
I was told it was under the dash, and thats only the cell box. Then told it was in the left fender and that was the XM radio.