Hi guys - just reassembling the MC28 after a total rebuild (roll pin in piston ring groove decided to come out )I am trying to set up the RC valves and the procedure shows that the servo motor should move to the "high" position when the TPS is disconnected , mine stays in the low position.I used the factory procedure of inserting a dowel in the valve body to position the valves then adjusted the tension on the cables .When I turn on the ignition , the servo goes to the L position - is this normal ?
I am getting an "Error3 " on the display , but if I turn off the ignition , open the throttle fully then turn on the ignition , there is no error on the display.does this suggest I have a faulty TPS ??

Measure the TPS resistance. The shop manual has the pin info and values. I think it's 5k max.

Thanks Eric - hope you're keeping well , appreciate the help { again) do you know if the servo is working correctly ? should it always be in the low position until the engine reaches a certain RPM ?

On the surface something doesn't seem right, but if the servo is moving at least we know its sorta functional. Before buying new parts, have you started the engine and observed what the RC valve does? It should move as you Rev the throttle. Have you measured the resistance of the TPS? You should be able to see the resistance as noted below.

Red to green should be 5k or so all the time.
Red to Blue should change as you open throttle. Range changes from I think close to zero to about 5k ohms. It should change resistance smoothly. An analog ohm meter works best here.
Green to Blue should change as you open throttle, but the change will be inverse of red to blue.

If the TPS is not giving correct resistance then pgm will not be able to correctly position rc valve.

You could also do some bench testing on the servo motor with a 12v battery. Do you have a copy of the schematic? It shows which pins voltage is applied to.

thanks for all your support Eric - I haven't started the engine yet - will do some checking as per your instructions