Quoted from Fred558:
So to narrow down the problem to the playfield I could disconnect the greenlight (+) power pin from the jack leading to the backbox. (correct me if I'm wrong)
If the green lights are still on then I know for sure some GI (+) is touching my green (+) somewhere on the playfield bottom.
I would first unplug the 7-pin connector on the front relay board and see if any of the green LEDs are ON.
This is the relay that turns the green ON when activated and the GI OFF. If this plug is disconnected, the green should not be ON. The GI should be OFF too unless you do the following.
If you are careful and go by the relay board diagram, you could test which lights turn ON/OFF by using a shorting wire (section of paper clip) inserted into the 7-pin plug thereby bypassing the relay. I would only recommend this if you are confident with what you are doing. For example, only connect COMM1 to NC1 or NO1 and COMM2 to NC2 or NO2. You can test which lights turn ON/OFF and if any are shorted. The pin numbers should be on either the plugs or the circuit board.
Pin 1 - 4: GI=ON, Green=OFF or
Pin 1 - 6: GI=OFF, Green=ON (on one side of playfield)
Pin 2 - 5: GI=ON, Green=OFF or
Pin 2 - 7: GI=OFF, Green=ON (on other side of playfield)
I would do these 4 test first and see what your results are.
The rear relay board is in series with the front relay board. If the rear solenoid is ON both GI and green are OFF. If the rear solenoid is OFF then GI or green are ON or OFF depending on the front relay.
Front relay OFF, rear relay OFF = GI ON, green OFF (normal play)
Front relay ON, rear relay OFF = GI OFF, green ON (condition green)
Rear relay ON = GI OFF, green OFF (attract mode) also the front relay should be OFF