I've searched and found others who have had the codes above, but I wanted to see if anyone has run into what happened to me today.
I haven't driven the truck in a few days. It's sat in the garage in Southern Indiana with slightly above normal temps. This morning I walk out and attempt to remote start it (like I always do, because I love the sound the GM Performance exhaust makes LOL) and the engine attempts to start, turning over very slowly what sounded like less than 2 times. Concerned I unlocked the truck and got in. Using the push button the engine turns over very slowly again 4-5 times and then starts. When it starts my compass tells me it needs to be calibrated, my fuel gauge shows absolutely empty (I had at least 1/4 tank), and my check engine light comes on. I turned it off, exited the truck to reset things. Restarted, was still slower than normal turning over, but it started quicker. The fuel gauge was still on absolute 0 and the check engine light was on. I called the dealer to make an appointment, and checked the codes with a scanner. I had 2 C0021, and 2 P25A2 codes (I have all updates and TSB's done as confirmed by the dealer).
I thought it might have been a battery issue, as my fuel gauge started going up as I was driving, finally getting to where it should have been by the time I got to the dealership, and the check engine light went off, because of course it did...
I spent 3 hours at the dealership, where they say they tested the battery, and all of the computers with nothing showing as wrong. The manager gave me his card and said to call his cell phone if the light comes back on and head in so they can test it when the light is on.
I guess my main question is does anyone here think this could be caused by the speed sensor staying on and draining the battery (even post TSB)? Or maybe something else electrical?
Thanks in advance for thoughts/options on this