Toyota Sienna 2009 Code P0705

A few months ago, check engine light, VSC, Trac off lights came on. And the Neutral and Drive lights turn on at the same time when in drive (the other gears just turn their on light fine). After several thousand kilometers, the car shifts and drives exactly the same as before.

The code (P0705) indicates the neutral safety switch. I have replaced the switch, reset the code, and the code and all the lights reappeared immediately.

At this stage I’m not sure what to troubleshoot next. I read somewhere that it could be a short in the transmission harness. What I’m not sure is how I would diagnose the harness. Is there anything obvious that I can test, to be able to tell if the problem is the transmission harness?