On the MC28 there is an easy to follow procedure, however, you do need to be able to splice into the wires to check this, or make some sort of inline connector that allows you to measure the voltage.

First measure the supply voltage across the outside two pins of the 3P connector for the TPS. It will be 4.5V - 5.5V. This is "Va".

Now use the following formula to to find the required voltage for WOT (Vo) and closed throttle (Vc) which is used to set the TPS correctly. Measure between Y/Bu and Bu/G wires.

WOT:

Vo = Va x 0.786 So, if you measure 5V then 5 x 0.786 = 3.93V
Vc = Va x 0.1 So, if you measure 5V then 5 x 0.1 = 0.5V

It's pretty simple.