As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START CABIN PRESSURE WARNING ANNUNCIATOR ILLUMINATED. CABIN MAX DIFF READS 7.5 WHEN CABIN NOT PRESSURIZED. PERFORMED SEVERAL STARTS, CABIN PRESS IND DID NOT ILLUMINATE, OPS CHECK GOOD EVERY TIME. COULD NOT DUPLICATE DISCREPANCY.