Hold on a sec.
Am I correct that this PCB is connected to the exit of the BI-DIRECTIONAL motor control PCB A-16120 ?
If so, then I would suggest not to install D1, the L6203 would not like that.

LeonsRIPMMTB TEH fix.jpg

If Leon's modification worked without a diode, then the L6203 is likely protected against voltage spike.
In the L6203 datasheet there are 2 diodes per channel so it looks like it won't need external diodes.
Maybe someone with knowledge about electronic components can give a more decisive answer.

6203-1.JPG

I think you have to experiment with this motor-control board.
This ic has the (used) ability to stop the motor instantly like a brake when both inputs are 'high'.
I don't know if this still works when external diodes are implemented but if it does, it indeed doesn't hurt.

If this only happens when trunk is rotating clockwise, then this would be a solution for the diodes as well.
leon mod.JPG

Does this happen in all software versions ?

I made a quick test setup to see if the diodes have any negative effect on the motor "brake" and they didn't.
So it is safe to use the flyback diodes.

test 123.jpg

The only thing I would change is the white text on the PCB at J2(-N) saying "20 Volt" and "GND" because:
1st - it is 12Volt and
2nd - the polarity changes when when motor is driven CCW or CW
so to avoid confusion call it something like motor a' and b'
motor a + b.JPG
label1.jpg

Yes, the wire colors assume it is 20V + GND but it is motor drive as we know

I have an unfounded preference for the "DUO LED 2 Pin" choice, maybe because the LEDs are directly on the motordrive and share one resistor.
duo led.jpg

thanks !

There was an animated .gif instruction in post #133.

https://pinside.com/pinball/forum/topic/tom-trunk-error-leons-fix-anyone-done-this/page/3#post-2661404

1st you want to know if the bi-dir-motor-board is controlled by the CPU/Powerdriverboard or the the bi-board has failed.

Unplug J126 from PDBoard and check if the LED goes OFF on the LEON-board.
If the motor-activity LED stays ON, the problem is on the bi-dir-motor-board

There is a piece of GI-wire under the motor control board. Can you verify if that doesn't make contact to the PCB

Can you unplug the lamp from the trunk, That is the connector under playfield with Yellow and Red wire.
Does that solve it ?

yea,

It does happen when the interruptor or opto fail, the trunk keeps rotating, damaging the harness and eventually get shorted.
That will give funny results in the lamp matrix.

trunk wire (resized).png

It could be that the insulation of the wires is damaged in the axis of the trunk, or diode is shorted at the lamp holder.
Something like that

That picture is correct.

inspect insulation of the wires and be sure the lamp holder doesn't touch any metal parts in the trunk.

true.

Check that as well. The mounting to the trunk shouldn't have electrical connection to the lugs of the lamp.

In other words, the screw that is used to mount the lampholder, should not touch the wires/lugs of the lamp