In order to properly dyno your MKV supra it is necessary to disable the different systems in the car that are made unhappy on the dyno due to differences in traction/wheel speed. To do so:
With the car off, click the car’s start button 3 times within .8 seconds with your foot OFF the brake. You should see a Diagnostic Mode message from the cluster.
Hold the Odometer Reset button for 10 seconds until “Main Menu” shows up and the option then release the button.
Click the Odometer release button to cycle through the menu until you get to the chassis option and then hold the button for 2 seconds.
The cluster should now ask to start “Dyno Mode.” Press the Odometer button once to confirm.
When you start the car Dyno mode will be active, to exit cycle the key off and on again.
Currently Dyno Mode has a speed limiter around 160mph
Additional Important Note:
With the electronic steering rack these vehicles are equipped with, it’s recommended to avoid strapping the vehicle down by the wheels. This can have the unintended effect of damaging the steering rack, steering position sensor, or otherwise altering what the rack believes is the center point of the system. Make sure to strap the vehicle down by another solid point on the chassis instead.