MTH Car Wash Trouble Shooting

The first and obvious thing is to check the wiring to it. This is because the lights are completely separate, and the motors and logic motion both has to have power and then ALSO be triggered to begin the action.

Also, like most of these accessories- the first task on power on  (before being triggered) is to move the accessory to the known parking state.This involves the motors running to their limit switches- and one key one- the door must first open fully, and THEN the car chain drive movement attempts to move forward. If the door motor cannot move or is faulted, and does not trip the open limit switch, then the next step cannot happen. This is because again, we start in an unknown state, the car could be be just before the door, so the door must open first (even if the car is not on the little tab).

Again, my first guess- failed wiring to properly power up the motor side of the accessory.

Failing that- improper trigger polarity or issue

Barring that- some stuck state where it cannot initialize to move to the parking state.

https://www.mthpartsandsales.c...lists/270?type=lists

If the motor drives were bad (example blown output transistors) you can still fake the funk by manually triggering the limit switches in sequence. Door open, door close, and the the limit switch for the track parking position in the front. Then trigger and sounds would start. It's just a sequence and what limit switch should be triggered when to move to the next step.

The manual https://mthtrains.com/sites/de...ction/30as12768i.pdf

The KEY point is that "D" and "E" are the logic or movement power contacts. "C" is the trigger contact.

A and B are just for the lights and do nothing else.

Everything Vernon said plus.  Note that the “A” terminal has 2 wires; the red power wire AND one of the black leads from the activation button.  If you miss that connection all you will have are lights.