What was found
ON TAXI OUT NR 2 GENERATOR FIELD RELAY TRIPPED. STRONG BURNING SMELL IN COCKPIT BEHIND ELECTRICAL CONTROL PANEL BULKHEAD. DISCONNECTED NR 2 GENERATOR CSD AND RETURNED TO BLOCK. NO FIRE NOTED. TROUBLESHOOTING REVEALED A WIRING PROBLEM AT NR 2 GENERATOR, CAUSING THE GENERATOR CONTROL UNIT IN THE COCKPIT TO OVERHEAT AND FAIL. WIRING AT THE GENERATOR WAS REPAIRED, GCU CHANGED AND SYSTEM OPERATED NORMAL. THE GCU CAUSED THE SMOKE.