As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE SELECTED GEAR UP NOSE GEAR INDICATED DOWN AND LOCKED. ALL 3 GEAR PINS WERE STOWED AND THERE WAS NO AIRFLOW NOISE ASSOCIATED WITH GEAR DOWN. COMPLETED NON NORMAL CHECKLIST AND GEAR CAME DOWN NORMAL. LOCK INTRANSIT LIGHT STANDBY UP GEAR WAS DOWN AND LOCKED. AIR RETURNED TO DTW. REPLACED LANDING GEAR CONTROL HANDLE. FOUND DOWNLOCK PROX SWITCH BAD. REPLACED PROX SWITCH.