What was found
INFLIGHT THE NR 1 AC GENERATOR CAUTION LIGHT ILLUMINATED. PERFORMED QRH, CYCLED SWITCH ONCE AND NR 1 AC GENERATOR REMAINS ILLUMINATED. AIRCRAFT RETURNED TO DTW. MAINTENANCE FOUND NR 1 AC GENERATOR CANNON PLUG TO BE CONTAMINATED, CLEANED OUT CONTAMINATION THOUROUGHLY. INSPECTED PLUG, NO OTHER DEFECTS NOTED, RESECURED PLUG. GROUND RAN ENGINE, OPS CHECK OF NR 1 AC GENERATOR SYSTEM GOOD.