How do I change shifting cylinoid A in the trans of my 2000 jeep grand cherokee?

If you have the 4.0 engine the "shift solenoid" is for overdrive and also one for tcc ingagement.There is however a govenor pressure solenoid and sensor that will affect shifting.If you have a v-8 engine then you have a solenoid block that contains all 6 solenoids for the transmission in one package and is mounted on the top of valve body inside the transmission.If you can tell me what the diagnostic codes and symptoms are I may can help you fix it without buying expensive parts you dont need.