Retitled post as I have not found the issue.
I am bench testing a sys. 6 driver with Leon's test rom and following Mark's guide to troubleshooting and repair http://www.flippers.info/system6repairpart5.asp
The first step is to test pins 2-17 on the 3 PIA's (for the one at IC11 says to ground pins on 2J3 to test OUTPUTS 2-9) I did this one pin at a time and get a pulse on each. Now under the switch matrix input test it calls these pins INPUTS and describes grounding each pin on conn. 2J3 and checking the PIA at IC10 (pins 2-9 I assume) for a pulse. The confusion I have is that these pins (2-17 on all 3 PIA's)were already checked for a pulse in the first step and now am being directed to check again but by grounding the pins at conn.2J3 one by one. Since these pins already have a signal/pulse how is checking them again going to matter? Why is PIA at IC11 said to have inputs at pins 2-9 and also outputs at pins 2-9? My guess is there is reference to the wrong pins or the wrong PIA in these instructions but I am not sure what the error is.