First thing is check the slam tilt and see if it got bent and is stuck closed, if so bend it open.

If it is good, then I'd check the wiring in the door harness next for shorts inside the harness.

LTG : )

Try removing the connector from the CPU for that switch line, at least you'll know where to look next. If problem remains it's on the CPU, if it goes away it's out in the game.

LTG : )

I am having this same issue on my Indy 500 and not sure if I know where the slam tilt switch is? Manual does not show slam tilt switch location. Is it the white push button inside the coin door?

Duhhhhhhhhhhhhhh!!!!!!! I got it!!!!

Had a similar issue when changing some ribbon cables. It was the short 34 pin that’s goes between the mpu snd driver. Reseated it and it worked