Rke new fob programming
 

Well, I’ll do this again, since the first one never posted! Was all set to drop my GS yesterday for the MRC upgrade, when I paused to try again to program my spare fob. The display (dic) never gave me the go ahead as the instructions stated it would, so I went through the motions anyway. After repeated try’s, nothing. Then my original stopped working, except for the doors and hatch. My new fob started to do the same crap, everything but start. Ok, time running out, so I called GM roadside. While waiting for the driver, I kept trying the remotes, even swapping batteries. 45 minutes later, with the driver admitting he really didn’t want to mess up my car, which was pointed in and the brake was on, so I concurred. Anyway, magically, it started. I guess the programming mode finally timed out?? So, it started, and I drove like a maniac to get to the dealer on time! This all started with same MRC UPGRADE problems as the others on here, with Chevrolet Performance stepping in and schooling my two local dealers. I’m headed out to get it, and I really hope the upgrade makes a difference!

My first thought was that your new fob is not a C7 fob, but rather a C6 fob.

Way back when I got the car in 2014, I tried to see if my extra C6 fob would work, so I attempted to program it. Well, not only did it not program, it temporarily, partially disabled my existing C7 fob, just like your story.

It wasn't until after the car timed out and went to sleep that my fob started working correctly.

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I was hoping it would time out, thankfully it did. I also bought my new GM fob from Amazon for $60, which was awesome, and the key for $6 on eBay. My local locksmith cut the key for $20

Had a similar experience. Wasn't seeing the expected DIC message after turning the key 5 times in the trunk latch. Next thing you know my working FOB is not working!
It went back to functioning a little while later. Turns out the wiring in my trunk latch was faulty. Someone else here also had that problem.