As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TOL - FLT 3378 - ON APROACH TO TOL, THE LEFT GREEN DOWNLOCK LIGHT FAILED TO ILLUMINATE AFTER GEAR EXTENSION. THE TRANSITION LIGHT WAS EXTINGUISHED. THE AIRCRAFT RETURNED TO DTW. MAINTENANCE REPAIRED A WIRE AT CANNON PLUG P1. ALL CHECKS SATISFACTORY. (X)