Hi, I have a 2001 GMC Denali and it wont start. When I turn the key the engine fires and turns but it wont stay on. I replaced the ECM,Fuel Pump, Spark Plugs, Wires and I checked all of the fuses and relays. The security light is on and also the OnStar light is red.
All this started a day after I programmed one of the keyless keyfobs. When I tried to check the computer through the data link connector the computer has trouble trying to connect, actually it doesnt connect at all. Any Ideas ?