Anti theft problems??

:frown: Is there any one out there with the problem of the anti theft light coming on while driving? I've had GMC look at my vehicle a number of times and they can't find the problem. Also, it goes into default mode, and will not start. Any feed back would be appreciated.

:frown: Is there any one out there with the problem of the anti theft light coming on while driving? I've had GMC look at my vehicle a number of times and they can't find the problem. Also, it goes into default mode, and will not start. Any feed back would be appreciated.I also have the same problem

If the security light comes on it stores a code in the PCM and the BCM.
There are some GM service bulletins pertaining to intermittant security problems and no start conditions.
Take it back to the dealer and have them fix the problem (the repair is not that difficult)

The most common cause of this condition involves replacing the lock cylinder housing, it contains a hall effect sensor & the ignition switch. Some also put in a new cylinder, it has a magnet that triggers the sensor & monitors the rotation.