The Passlock system is a theft-deterrent system, used in General Motors vehicles, which is designed to ensure that the car does not start if the right key is not in the ignition. It works by sending an encoded password to the power train control module when the key is turned. If the password is correct, the car starts. However, a couple of problems with this system have arisen in cars such as the Chevrolet Impala.
When the Passlock system fails, the Impala cannot start. Some Impala owners have reported an inability to start the car even after waiting overnight, a problem that has been known to occur frequently in many GM cars and trucks. In many instances, the security light comes on as well, a glitch that seems in some cases to be connected to the Passlock failure.
In some cases, the Chevrolet Impala's Passlock system fails only temporarily. Owners have reported that in several instances, if they wait from 10 to 30 minutes after first attempting to turn over their ignitions, their cars start. However, most add that the car stalls again within minutes and often cannot be restarted.
Passlock problems became so widespread that General Motors released service bulletins to car dealers relating to Passlock system failure on many of its models, particularly the 2002 Impala. GM also released bulletins relating to several other electrical ignition system issues in the Impala, including the wiring of the security indicator light.
