Just thought I'd share in case anyone else deals with this. My local mechanic went through the diagnostics for an open diff lock circuit error, c1340. Wiring seems to be good, but struggles to get into 4l; didn't work when mechanic tried. Let me know that it was likely the 4wd actuator or 4wd ecu and that I would need to take it to a transmission shop or the dealer. Want it done right, so I chose a nearby yota dealer with a good rep. That was yesterday morning. They called me yesterday evening and and still running through the diagnostics. Let me know that the wiring looked good. Asked me questions about how often I used 4l and if it happened on the trail or road. I use 4l about 3 or 4 times a year. I don't cycle my 4h and 4l monthly as I should. I have about 180k smiles on her. Dealer seemed unsure what was wrong saying that c1340 could mean other probs like abs. I have a feeling this could be expensive...