I was thinking along the same line's of trying to Isolate it (something, anything
)!
Also would it be possible to bypass the GPS by permenantly grounding the 3rd gear wire, while leaving the neutral wire connected, thereby allowing the neutral light to still operate, but once taken out of neutral the PGM will 'think' it's in third gear all of the time?
Just trying to build up an armoury of temporary "bodges" (hey I'm a farmer), just incase the p/valve and TPS trick's don't reveal anything.
To be continued.....
Regard's Phil
'If in doubt, Bodge It'