Working on a T2 today. Whenever the gun is loaded it immediately slam tilts. I have gone into switch test and everything shows normal and all switches when closed are reflected properly by name. However, when I close the coin door and the switch engages, the 3 targets and gun switch now show completely different names. In fact when you go into the switch test, each switch engaged on column 3 lights up the same switch equivalent in column 2. Open the coin door and everything shows fine.

Also, the left flipper engages the start button and adds players whenever it is engaged. The start button on the matrix is directly below the left flipper.

I have checked the diodes on the interface board.

I have also replaced the switch matrix IC on the CPU board.

Any help is appreciated.

Thanks Lloyd - figured it out. All the issues were caused by the 'mark' switch for the gun. Two of the microswitch leads were touching and causing everything to flip out.

Thomas