That depends on the make and model of the transmission. Please ask a new question and include year, make, model, engine size.
All solenoid are in the block on the front of the transmission case.
where is the transmission shift solenoid located on a 2001 Mazda protege
Inside t he large block on the front of the transmission, below the cooler hoses.
The 2002 Kia shift solenoid is located on the back of the transmission. The shift solenoid will be in the upper right-hand corner of the transmission.
The transmission shift solenoid on a 2000 Saturn 2L is located inside the transmission. It is typically located on the valve body, which is inside the transmission case. To access and replace the shift solenoid, the transmission will likely need to be partially disassembled.
The transmission shift solenoid on a Volvo s80 is located in the gearbox. It is inside the side cover and not easy to reach.
it is a transmission part
It is bolted into the valve body in the transmission. You will have to remove the transmission pan that is bolted to the bottom of the transmission to service the shift solenoids.
Inside the transmission
Located under the battery mounted onto the transmission
The transmission computer uses sensors located on both the engine and transmission for shift timing.
its inside the transmission by the oil pan