As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT MAIN LANDING GEAR RED LIGHT ILLUMINATED WHEN GEAR WAS RAISED. LANDING GEAR EXTENDED NORMAL. SIMULATED GEAR RETRACTION AND EXTENSION WITH PLATES AND FERRIS METAL BLOCKS. ALL CHECK NORMAL.REF MM 32-61-00. A/C OK TO CONTINUE. CREW DECLARED EMERGENCY LANDING IN EWR.