GMC 2003 Sierra - Manual (Page 107)

Passlock®
Your vehicle as equipped with the
Pflsslock'^ thefl’^eterrent system.
PassjcKk^is a passive thefl-tieierrent system
PassJock* enabies fuei if the ignilic?n Jock cyiinder is
turned with a vaiid key, if a correct key is not used or the
ignition iook cylinder is taitiperod with, luei is disabied.
il the engine stalls end Ihe security tight fiashas,
wait untii the light stops hashing before trying to teslarl
the engine. Remember to release the key frarri
START as soon as Ihe engine starts.
li the engine is running and the securty iight coimes on,
you will be abie to restart the engine it you turn the
engine off. However, your Passlock^ system is
not working properiy and must be serviced by your
deaten Your vehicie is not proteded by Passiock^ at this
Cme. You may also want to check the fuse (see
Fuses and Circuif Bfeakers on page 5-f IT) See your
dealer for service.
in an emergency, call the GM Roadside Assistance
CEnJor, Sae flaadsj'fie Ass/stertce Program on page 7-6
under Customer Assistance Information.