The worn out switch can cause a few problems, most notably a no start or intermittent start condition. The intermittent start condition is when sometimes it takes a few turns of the key for the switch to make good enough contact to then activate the starter. The no start condition usually is a result of the worn contacts in the switch causing an interruption of the communication between the BCM (body control module) and the PCM (power-train control module). This communication check is part of the Pass Lock system that controls the Anit-Theft system in which it disables the fuel pump relay and the starter relay to prevent theft. However sometimes a faulty ignition switch can cause a false positive for the Pass Lock anti theft system. For a details on how to reset the Pass Lock see the end of this post. However if you came here to replace your ignition switch on your GM vehicle, watch the video below as well as the pictures on how to remove the dash components to access the switch mechanism.
This ignition switch replacement applies to the following vehicles as they use the same switch part number.
CHEVROLETIMPALA 2000-2005
CHEVROLETMALIBU 1997-2001
CHEVROLETMONTE CARLO 2000-2005
OLDSMOBILEALERO 1999-2001
OLDSMOBILECUTLASS 1997-1999
OLDSMOBILEINTRIGUE 1998-2002
PONTIACGRAND AM 1999-2001

1. Insert ignition key and turn to the “ON” position. Do not attempt to start the engine. Leave the key in the “ON” position for approximately 11 minutes. The security light will be steady on or flashing for the 11-minute period. Do not proceed to Step 2 until the security light turns off or stops flashing.
2. Turn the ignition switch to the “OFF” position for 30 seconds.
3. Turn the ignition switch to the “ON” position as in Step 1 for 11 minutes.
4. Turn the ignition switch to the “OFF” position for 30 seconds.
5. Turn the ignition switch to the “ON” position as in Step 1 for 11 minutes for a third time.
6. Turn the ignition switch to the “OFF” position for 30 seconds for a third time. 7. Turn the ignition switch to the “ON” position for 30 seconds.
8. Turn the ignition switch to the “OFF” position.
9. Attempt to start the engine. If the engine starts and runs, the relearn is complete.