What was found
ON TAXI OUT FROM THE GATE, CREW RECEIVED AN ADS 2 HEATER FAULT EICAS MESSAGE FOLLOWED BY AN ELECTRICAL SMOKE SMELL IN THE COCKPIT. AIRCRAFT RETURNED TO GATE. MAINT FOUND WIRES TO THE TAT 2 PROBE BURNED AND PINS MELTED. THE TAT2 SENSOR, CONNECTOR PLUG AND ADSP4 PROBE WERE REPLACED. TAT 2 PROBE PN 102AW1AF.