TM  10-3930-669-20 1.  DRIVE AXLE OVERHEATING (CONT). KNOWN INFO Engine temperature 105°F or over. Glow plug indicator operates. Drive axle oil cooler ground wire OK. Drive axle oil cooler OK. Relay R7 ground wire OK. Wire 29 to relay R7 OK. Wire 73 OK. Relay R7 OK. Wire 29 to engine temperature switch OK. Engine temperature switch OK. Wire 71 OK. Parking brake OK. Axle oil pump ground wire OK. Axle oil pump OK. Relay R8 ground wire OK. Wire 29 to relay R8 OK. Wire 74 OK. Relay Re OK. Wire 29 to drive axle temperature switch OK. Drive axle oil temperature switch OK. Wire 72 OK. POSSIBLE PROBLEMS Brake fluid faulty. Drive axle oil level incorrect. Master cylinder faulty. Drive axle faulty. TEST OPTIONS Visual inspection. REASON FOR QUESTION If    brake    fluid    is    incorrect, drive axle will overheat. 2-338