pdxnerd

The last few years the onstar module was behind the infotainment screen, in the 2018 it was relocated to under the passengers seat, far right, behind the bose module. Here's my process for removing the antenna circuit board, which disables onstar by disabling the cellular modem and the wifi hotspot. Afterwards the Bluetooth works, the Nav still works, the mic still works for commands. What will Not work is onstar, wifi, the cellular modem (used for wifi and onstar), and the compass. The Nav shows GPS with a crossout but the nav still works, including traffic (that’s from the satellite data)



Step 1. Remove the glovebox. I had to squeeze the sides inwards, almost pushing one in until it clicked out of the groove then do the other side. There's a catch in the right side that needs to be slid towards you to free the tension cable. After that rotate it down and remove the 2 dowels holding the bottom in.




Step 2: Remove plastic covers. First there's a plastic panel that is held in by 5 screws (star bit needed), and 1 plastic push lock. Second plastic cover is the fuse bot cover. There's one fat thumb plastic screw on the back floor piece, then pop the plastic out, pulling inwards from the furthest back is the easiest if memory serves.




Step 3, Remove cabling. So there is adequate clearance, remove the two large cables going into the fuse box (front and back, one blue one white). As well as the hvac box cable just above those cables, and pull the clip off holding that cable up.





Step4. Remove the Bose box. There are 2 screws and 1 bolt to be removed to free the bracket holding the bose box. Once free reach through the top hole and remove the cables. the tabs are on the right side, there are 4 and the 3rd down has a red catch you'll have to pull towards you first. Once those cables are free work/slide the unit out the bottom. The cables should be able to move out of the way now to facilitate this.





Step 5. Remove onstar box. The onstar box should now be visible. its being held in by two plastic clips on top, and one on bottom. If you pull the bottom clip out of the way you can pull the box loose. On the backside there are 2 white cable brackets up top and two antenna connections on the bottom. Remove these and slide the box down passed the fuse box (like the bose box path).




Step 6. Open this box and remove the top board to access the smaller antenna board. Remove the smaller board and put the larger back in.




Step 7, reassemble in reverse order!