Definitly should be running a plc board in the dash.

I was re reading your earlier responses and need clarification. When you said you checked the rear prox switches and both lights are on what do you mean. Only one prox switch on the rear should be lit up at a time.

And when your checking them are you turning the rear tire all the way to the 90 position touching the stop bolt to the frame, checking to see if it is being turned on and that the air gap is no larger then 8mm. (As well as checking to make sure the other 0 degree prox switch is Off)?

But if your correct and saying everything is good with the rear prox switches i would

Check relay 9 terminal 30 for 12v. If it has 12v jump to terminal 87 to bypass the relay and see if the change over valve (6port) operates.

If it doesnt its wiring or connector issue.

If it does operate check relay 9 terminals 85 and 86. One should have ground and the other should have 12v after the plc board has recieved a signal from the rear 90 prox switch and the directional lever is in the right or left position.