As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TUS - AIRCRAFT RETURNED TO FIELD WHEN THE AFT CARGO DOOR CAUTION LIGHT ILLUMINATED. MAINTENANCE INSPECTED THE AIRCRAFT AND REPLACED THE CARGO DOOR PROXIMITY SWITCH. AN OPERATIONAL CHECK WAS PERFORMED AND CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.