What was found
(CAN) FLIGHT CREW REPORTED A CABIN PRESS CONTROLLER FAULT MESSAGE CLIMBING THROUGH 17000`. DIFFERENTIAL SHOWED 6 AND CABIN 2500` ALT. THIS WAS FOLLOWED BY 12000` WITH CONTROL AGAIN. MAINTENANCE TROUBLESHOOTING WAS ACCOMPLISHED AND ULTIMATELY THE GROUND CONNECTION CHECK VALVE WAS REPLACED IAW AMM 21-23-06-400-801. PX RUN COMPLETED IAW AMM 21-31-00-710-801. NO FURTHER FAULT WAS FOUND AND THE SYSTEM WAS CHECKED SERVICEABLE. AIRCRAFT HOURS: 20215:29. AIRCRAFT CYCLES: 20130. (TC# 20190307001)