As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE BACK LIGHTING ON THE FLT ALT AND LAND ALT DIGITAL DISPLAY HAS GONE BLANK. ACFT GROUNDED. REPLACED CABIN PRESSURE CONTROL MODULE IAW AMM 21-31-02-400-801 & 21-31-02-000-801. SYSTEM CM TEST NORMAL, GROUND VERIFICATION SUCCESSFUL, ACFT OK FOR SERVICE.