I ordered a preprogrammed to the vin# PCM for my 03 GMC Sonoma SLS after I installed it my truck will turn over but won't run, I haven't seen a padlock on the dash but the security light above the rpm tac and speedometer stayed on, so I went through the key relearn process and the first time the security light stayed on for 10 minutes but after that it only came on for a few seconds then went off but I followed the steps all the way through as instructed but it still doesn't start , what do I need to do ?

1 Answer 1


You need to program the pass lock

  • Turn ignition to "ON" position for 11 minutes. The light will cut off.

  • Turn switch off and then turn the ignition back to "ON position for 11 minutes.

  • Turn switch off. One more time, Ignition "ON" for 11 minutes. Switch off and wait 10 seconds or so.


  • If the above Passlock relearn procedure is successful and security (symbol of car with a large padlock) cycles on then off when ignition is turned on and the engine won't startup, the problem isn't a security issue disabling engine startup.
    – F Dryer
    Dec 8, 2022 at 17:18
  • I tried that and it still won't work but I also found out that you have to have atleast 1 of the original factory keys and all I was given when I bought the truck was an aftermarket key that someone had made for it at some point and I was told that now I have to go to a dealership and get an original key in order for it to work , so I'm gonna try that and see where I get with it !
    – Nate
    Dec 13, 2022 at 0:35
  • Aftermarket vs. Original doesn't matter at all. There is no chip in these keys its just brass. The security sensor is between the ignition cylinder and on a device on the column. Nothing to do with the key. The ECU is probably not programmed right.
    – narkeleptk
    Dec 13, 2022 at 15:08

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .