On-board diagnostics are enabled when the SW1 and SW2 of the Game Select dip switch are on or in the up position. This will allow you to use the features of the Ultimate MPU Test Card. Then consult the Ultimate MPU Test Card manual for instructions on running the different test. Remember if you didn't purchase The Ultimate MPU Test Card you still have the built in self-test diagnostics using the push button on the door or the switch built into the new MPU board