TM 9-2320-302-10 0010 00-3 Table 1. Troubleshooting Procedures - Continued. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 4.  Trailer Brakes Will Not Release - Continued. 3.  Check intervehicular air    hoses    for    proper connections. Connect air hoses. 4.  Check vehicle air system for leaks. If leaks are found, notify Unit Maintenance 5.  If  leaks  are  not  found and vehicle components     are     not damaged, troubleshoot semitrailer. DRIVELINE LOCKING SYSTEM Driveline     Will     Not     Disengage When Inter-axle Lockout Control Valve Lever is Moved to UNLOCK Position. 1.  Ensure system has had enough time to disengage. Leave lockout control valve lever in UNLOCKED position and  wait  for  light  to  go off. 2.  Excessive driveline windup may have occurred.   Back   truck up  slowly.  If  driveline does not disengage, notify   Unit   Mainten- ance. ELECTRICAL SYSTEM One or More Lighting Systems Not Working. 1.  Check position of switch(es). If vehicle is coupled  to  semitrailer and   problem   is   with semitrailer lighting system, check intervehicular cable connection. Place   switch(es)   in   ON position and blackout light switch to NORMAL position. Connect intervehicular cable. 2.  Perform semitrailer troubleshooting.