2000 GMC SIERRA SHIFTS HARD AFTER WARMUP.

Solenoids inside the transmission or the control module.

Probably needs a good flush and new filter

are you sure is the transmission which is giving you the noise or the differential ? check it out first .

changing the transmission is not an option as it is working good
the problem will be an actuator or servo/solenoid
take it to an auto transmission specialist professional and have it properly diagnosed

replace the sensor. Tim

check that the fluid is the right amount mate,or check for any vacuum hoses that may have disconnected accidentally,if it isnt any of those,try adjusting the kickdown cable,good luck

rec check fluid first. If trans fluid hasn't been changed in last 30,000 miles change fluid, filter and pan gasket. At that time inspect for foreign materials in bottom of pan or on magnet if you have one. If truck has over 100K and fluid was never changed you may have more problems if changing the fluid.

First check the adjustment at the transmission lever were the cable attaches to. If it shifts into every other gear just fine the locking parking pawl has been worn away or broken. The pawl has a pointed 90 degree end that catches into the drum inside the transmission. It suppose to catch into a cogged tooth area of this drum causing the trans to lock in place.. It will be cheaper to service the emergency brakes if not working properly until you can finace the cost to repair the trans lock. This will cost a sizable amout to repair I know.

i gather its an auto transmission ,which mean your loosing oil pressure from the convertor inside the tranny housing.

More then likely the cable from the shift lock solenoid that unlocks the shifter is binding up or the shift lock solenoid is sticking..