WMS Model 400 High Speed Slant Top with Bonus Round Emergency Lights not working

[Scoot]

I acquired this machine in rough shape and decided to purchase a new CPU with Game and Sound EPROMS, and a new I/O Board. This game originally had the first of 3 revised boards and still has the first Backplane board and not sure the compatibility. The new boards are 3rd revision boards. The power supply has been upgraded. At this point I have ran a full clear and the machine seems to be functioning correctly and man the payback has to be in the 80% range as it is TIGHT. My problem is that when the Bonus round is hit and the reels spin…the Emergency cop car lights at the top of the machine do not light up or flash. I have inspected all wiring and boards finding nothing apparent. I have studied the schematics and I am cannot see what triggers and makes the lights flash during the bonus round. I thought it might be SW2 dip switches (all in off position), but not confident in trying that. I also swapped out another Good I/O board with no results. I verified all wiring contacts and the wiring configuration is strange as it does not appear to have solid grounds. I also realized that this machine also was built without these lights like the tall round top version as well as some slant tops. So…I wonder if there are different game EPROMS that accommodate this function and that I acquired the incorrect version that does not have this function in the chip. I am out of ideas and need direction. I hope it’s because I can’t see the forest for the trees. I will provide schematics, photos, whatever is needed.
Thank you much!
 

[dragster73]

Check for power at the lamps. I’m assuming they are 12 volt lamps. You will have power to the lamps all the time and the I/O board supplies the ground when it’s time to turn the lights on. I highly doubt this is a software issue. If the lamps have power to them I would trace the ground return wires from the lamps to the I/O board. If there is not power to the lamps then you’ll need to figure out why it’s missing.