P1 Planetary Carrier Thrust Washer Inspection
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, 2003 Chevrolet Cab & Chassis Silverado, and 2002 GMC Sierra. However, it is still accessible from the selected car via links, so may be relevant.
Measure thickness of thrust washer in at least 3 locations. Compare measurements to specifications. See PLANETARY GEAR MODULE SPECIFICATIONS table under TRANSMISSION SPECIFICATIONS. If thickness is less than minimum specification, replace thrust washer.