99 gmc,,, problem......

wut do they flash it with? a scanner?

reflash or reprogram a gm ecm is done with a tech2 gm scan tool only!
take it to a dealership and pay the 80bux or sit on here all day and waste your time.
The dealership has the latest software downloaded everyday and they can find out what is wrong very easily.

karl what code did autozone give ya?
i can look into it at the dealership i work at if you want?

im not sure wut the code wuz i think its P0452?!?!? not sure but its the code for emission control and im pretty sure its cuz i took the smog pump out but that was like 6 months ago

you might as well put a carb on it then

heck no the truck will never start again if i do that

if the security light is going off you need to fix that first, your truck will do exactly as described start and immediately shut off if there is a problem with your passlock function. put key in and turn it on until light goes off. turn off and back on until goes off again and do one more time and see what it does.

i have the same thing with my '01 s10, but i've replaced the ecm and reprogrammed it when we did so and still nothing. any more suggestions?

ok so i tried turning the key on and off and then doing it three times like u said jeremiah but still no dice... but thank you 4 tryin to help man im takin it into my friends shop today to put it on the computer so hopfully i find sumthin out!!! but thanks again to all of u!!! ill reply when i find out wut it is for sure so maybe we have sum more input 4 sum 1 else but thanks again all of u 4 takin the time...

ok so my truck is fixed !!!!!!!!!! its been done since last saturday but i havnt had time to get on here ,,, but they figured it out and it did need to be flashed with the computer but for all of you that may incounter this problem u dont need to take it to the dealership just find an auto shop or friend with a diognostic computer and u can flash it with that!!!!!! i had mine done for $65 bucks.... thanks again for all the help!!!