Have a stock 04 suburban Z71 5.3, 4X4, code Z for flex fuel. It was running fine, shut it off to get daughter from day care. Started engine idled terrible, put it in drive and it started to roll backwards while in drive on a flat surface. It then died and won't start. It will crank all day but won't start. This is how my wife told me the story.
I checked it with a tech 2 and got a SRS U1000 and 2 ACM U1301 codes. I have seen in other forums that the U1301 codes are a class 2 Data Link High and that the U1000 code is a class 2 Communication Malfunction. I checked the connections at the ECM as best as I could and cleared the codes. It still won't start and now just gives me a DSW B0229 code which I believe is a HVAC code. I am leaning towards the possability that the ECM has gone bad, does anyone else have any ideas before I drop a few hundred on a new one.

 

When you clear the codes do they come back as soon as you start the engine again. I had an ecm go bad on a 97 S-10 blazer and the codes would not clear, it also was showing that the voltage was 25.3 which says it was fried some how buy the person I bought it from. Just my thoughts.