You do NOT want to service the Toyota sealed transmissions unless you know what you are doing. And draining and haphazardly adding fluid in through the dipstick is a good way to jack up your Toyota transmission.
The Toyota transmissions are engineered to be virtually maintenance and repair free. And they pretty much are.
But if you are DYING to replace that fluid, this is the process for Gen4 and above Toyota AT's:
1) Make sure truck is level. Use the Toyota branded fluid. Drain, and replace with slightly more ATF fluid than you took out, through the dipstick (there is no fill plug)
2) Make SURE to use the required Toyota procedure. This consists of putting the truck in a "AT Temperature Check" mode. To do this, you use a piece of wire (or wires) to jump certain pins in your ODB2 port.
3) Then, there is a shift pattern you cycle through to put the truck into the diagnostic mode. With the engine running, you wait for the appropriate dash lights to signal that the ATF fluid is at the precise temperature.
4) While that light is on, you open the overflow valve, and let the ATF fluid drain until it stops dripping. Now the fluid is at the EXACT level.
5) Do not drain the excess while the light is off. If the light comes on and turns off because the fluid got TOO warm before you drained it all, STOP, let the truck cool, and repeat steps 2 thru 4.
You may want to Google or call Toyota for the specifics on the ODB2 jumps and shift pattern - I just don't remember. I know the above, because my buddy is a master Toyota tech, and I helped him change the ATF fluid on his 2008 Tundra @ 300,000 miles (for the first time). He was so unfamiliar with the process (because he almost never does it at the dealership shop) that he brought the printed out Toyota specs on the process.
Last edited by duck911; 11/17/18.
