GM Anti Theft System Usage

When diagnosing a no start condition these days, it's always a good idea to consider if the vehicle has a theft deterrent system that could be the cause. There's nothing more frustrating than chasing, say, a no crank, or a start and stall, only to find that the system is "only doing its job"! On many older vehicles, you can only check with the owner to see what, if any, after-market " alarm" may have been added. Car companies have increasingly made their own systems available either as options or standard equipment.