Game still boots into audit mode with at least 3.9 VDC at IC19 pin 22.

Audit mode with good battery voltage

Cause: Almost always a failed 5101 RAM at IC19.

Checks

• Confirm the voltage at IC19 pin 22.

Fix

• Replace the 5101 at IC19; some boards are fussy, so try several 5101s if the first does not clear it.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• How System 3 audit mode looks
• System 3 audit mode looks different
• Boots into audit mode every power-up with good batteries: bad 5101 RAM
• Reading the software ID in audit 00
• Game always powers up in audit mode: bad 5101 memory chip
• Running Leon's test EPROM with the boards still in the game
• Install the Andre Boot test ROM
• Use Leon's test EPROM, not the Williams one, for boot faults

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)