Does anyone have any experience with this code? All I could find online and T4R search is that this code was specifically added to 2002 4Runners, and doesn't apparently exist in any other models of 3rd gens.

my 4WD actuator failed last year, so I replaced the front diff ADD actuator and swapped the original transfer case for a junkyard part that worked flawlessly for about 10 months until it started throwing this P1783 code, and now it takes 5ish miles of driving at different speeds to get the AWD to engage/disengage. I've tried all the tricks to get it to engage faster, but nothing seems to work other than extensive mileage- even putting the vehicle into low range just results in 2WD low, there is no automatic change to 4WD thats supposed to happen.

My shop said there is not a specific 4WD position sensor to replace either.

I have no first hand experience with that code, but typically electronically actuated transfer cases monitor the 4wd position internally to the actuator. Sorry I can't be of any more help than that.

EDIT: Ignore me, I misunderstood what you wrote.

Fsm pages indicate transfer neutral switch malfunction. attached pages might help.

Attached Images

     

Thanks for the diagram! When work calms down a little I'll check this out and report back.