How do you change key and tumbler in 2001 gmc jimmy?

To change the key and tumbler in a 2001 GMC Jimmy, first, ensure the ignition is in the OFF position and disconnect the battery. Remove the steering column covers to access the ignition switch. Use a small tool to press the pin on the switch and turn the key to the "Run" position to release the tumbler. Once removed, install the new tumbler by aligning it and locking it in place before reassembling the steering column and reconnecting the battery.