None of the flashers light, in a game or in test mode, although the fuses read good. In solenoid test the coils don't fire either, yet they all work in a game.

No flashers in game or test, and coils won't fire in test: bulbs and coin door interlock

Cause: The backbox flashers were wedge bulbs (LED replacements here) that were not seated properly in their sockets or had failed. Coils not firing in test is normal with the coin door open: the door's interlock switch cuts the high voltage to the coils.

Checks

• Pull and reseat each backbox flasher bulb, and try a known-good bulb in a socket that stays dark.
• Check for damaged socket wiring where a working bulb still won't light.
• For coil tests, press in (or pull out to latch) the coin door interlock switch.

Fix

• Reseat or replace the flasher bulbs and repair any bad sockets.

Systems

• WPC DCS

Games

• Judge Dredd

Related tips

• A coil does nothing although its fuse is good
• Coin-door interlock cuts coil power on 1993 and later games
• No 50 V coils work
• No flashers work
• A solenoid will not fire in the solenoid test
• No coils work at all, fuses are good
• One coil will not fire
• Firing each coil from the WPC solenoid test

Source: Pinball Repair help group!! (Facebook group)