GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hi and thank you for your question. I wish I could give you the great news you're hoping for, but unfortunately OnStar / GM have rendered all vehicles built prior to 2008 inoperative for OnStar. The digital upgrade you are referring to was for some models, but none built prior to 2007. There is no option to upgrade / add OnStar on your vehicle. Again, I'm sorry to be the bearer of bad news.
GM was required to render all OnStar analog systems inoperative in 2008 (reference special policy 08089C, Doc ID#2210948) by the FCC. Any GM dealer can print these documents for you. However, something I missed and was not aware of is, in January of this year, it appears GM has made OnStar upgrades available to those vehicles that previously were rendered inoperative. GM has released digital equivalent VCIMs (Vehicle Communication Interface Module) for these particular vehicles. You will have to ask your local dealer what they would charge you for the upgrade. I do not have access to the price of the new VCIMs, or what their labor charges may be. My apologies for the confusion and thank you for the extra information.