What was found
HOT BRAKE NR 5 INDICATION BEFORE TAKEOFF. BRAKE FANS WERE APPLIED AND TEMP GOT INTO NORMAL RANGE FOR TAKEOFF. PASSING 13,000 FT ON DEPARTURE, HOT BRAKE INDICATION WITH NR 5 READING 500-600 DEGREES. ELECTED TO AIRBORNE RETURN TO ORD. BRAKES DID RETURN TO NORMAL TEMP ABOUT 10 MINS PRIOR TO LANDING. AT BLOCK IN, NOTICED NR 5 TEMP INDICATING 80 DEG WITH TEMP WITH SENSOR DISCONNECTED IAW MEL AND NR 2 TEMP INDICATING 0 DEG. INSTALLED SERVICEABLE BRAKE TEMP DETECTION UNIT AND NR 5 TEMP INDICATED 0 DEG WITH SENSOR DISCONNECTED AND NORMAL BRAKE TEMP WITH SENSOR CONNECTED BUT NR 2 STILL READING 0 DEG. INSTALLED NEW SENSOR IN NR 2 POSITION AS NEEDED AND ALL INDICATIONS NOW INDICATE CORRECTLY. OKAY FOR SERVICE.