toshiba plc ex100 run light problem

hello run light on ex100 pu12a not coming on when plc is powered up.
tried replacing :ex100
chassis
power supply
still no run light. any help please

Should run light come on as soon as keyswitch is set to run

Guessing here. Bad I/O module or programming? Try removing all but CPU, write and upload a program to the CPU with just the END instruction, then test. If it will go into RUN then power down, re-insert each module one-by-one, then re-test.

Link to manual:
http://www.toshiba.com/ind/data/tag_files/EX20_40%20Plus%20Manual_506.pdf