Dummy throwing turnouts.

Lack of pickup rollers has nothing to do with throwing a switch. For that matter neither should the wheels being electrically connected.

This is not a 2rail/3rail switchable loco either (not that it should matter) so there is nothing special about the wheels.

I think you have a different problem and a bit of a placebo effect here thinking it's due to conversion to a dummy.

Again- that's not how switches detect anti-derailing function, and this being the dummy should just be following the direction of the lead engine, so no reason for the switch to change.

I agree with Vernon.

I'd look at the wheels and trucks on the engine. Something is causing it to pick the turnout.

Is it the same one all the time?
Different ones?
What mfr turnout? would help with troubleshooting.

Have you tried putting the dummy in the lead position? Or even just reverse the direction? head-to-tail? Tail-to-tail?

It sounds like this engine's circuit board was fried because it had a short circuit issue to begin with.  Are the wheelsets out of spec?  Assuming your using Lionel nonderailing type switches, perhaps a wheel set is bridging the center rail to the outside rail. Try pushing the engine alone on energized track, by hand, thru a switch and carefully observe the wheel's tracking through it. Good luck...

And here I thought the title of your post was referring to the person throwing the turnouts..lol

What type of switches are you using?

You could also put the dummy as the last car of the train and see if the switch gets thrown right as it is going over. That will definitely confirm it is the dummy engine and not another random event.

Do the trucks turn freely? Are the switches on a curve? Does it throw the switch or pick the points? Both directions? Keep the info coming.