My GV Overdrive went on the blink a couple weeks ago and finally had time to trouble shoot it. I started with the easily accessible stuff and thankfully found it right away.
The button/switch on the manual gear shift has two bullet connectors GV supplied that feed into a little snap in telephone style connection adapter pigtail just before the controller, about 4" or so long. It grounds the milli-volt relay that powers the 12 volt solenoid to engage the OD.
I unplugged that phone connector from the controller and hit it with Electric Clean, plugged it back in...no dice.
Next I unplugged the two bullet connectors at the other end of the pigtail and hit them with Electric Clean, they tested with good continuity with the ohm meter so I knew the button was good, re-connected and... Bingo!
Dirty/bad connection at the bullets was the problem. I was a happy camper!
