Pressing the coin door Advance button does nothing; the game won't go into the test menu.

Coin door test buttons won't enter diagnostics: jumper test at the CPU plug

Cause: The coin door service buttons are wired as dedicated inputs to a small plug at the lower left of the CPU board, not through the switch matrix. Here the harness plug for one of those headers was missing.

Checks

• Find the two 4-pin plugs at the lower left of the CPU board; one has black wires and one coloured wires.
• Unplug the coloured-wire plug and briefly touch header pins 2 and 3 together. If the game enters service mode, the CPU is fine and the fault is in the coin door wiring or switches.

Fix

• Repair or replace the coin door harness and plug, or the faulty service switch.

Systems

• Williams System 11B

Games

• Police Force

Related tips

• System 11 CPU board connectors
• Lamps under the slingshots out: wire in the wrong position in interconnect plug J12
• Coin door test buttons and special solenoid switches are outside the matrix
• Listen for flipper relay K1 when entering diagnostics
• CPU sound diagnostic switch SW1 results
• Jokerz: CPU jumpers needed for its stereo sound board
• No plug at CPU 1J18 means CPU-controlled special solenoids
• No flippers at all: flipper relay K1 not pulling in

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