lennox rooftop unit

[redroge]

I,ve got a lennox rooftop heatpump unit with a kp17 comfort controller ,the controller is showing Pb com fault (communication error),the interconnecting wirings ok as i,ve connected the controller directly to the outdoor unit which leaves either the kp17 controller,kp18 interface or the kp01 master module at fault, has anyone come across this problem before if so what was the answer.
cheers
Redroge

[install monkey]

which pizza hut you on? haha . its a common fault- check your connections , if ok then its a new pcb

[install monkey]

check the fuses on kp01 and your kp17 is plugged into terminal j22 http://www.mediafire.com/view/?fpz6dcwcizlepzc

[redroge]

I,ve got 5vdc to the kp18 and 11vdc to the kp17 and yes its plugged into j22 ,main pcb or kp18?