TM 9-2320-363-20-1 This section covers the equipment and procedures used to     find     and     correct     Central     Tire     Inflation     System problems. Test Equipment Central    Tire    Inflation    System    troubleshooting    can    be performed at three levels: Electronic Control Unit light codes Hand-held tester Personal computer based diagnostics Regardless of the testing equipment used, the troubleshooting    procedures    will    be    based    upon    the diagnostic  service  codes.    The  hand-held  tester  and  the personal    computer    system    offer    the    advantages    of computer-aided testing without interpreting service codes. Each light sequence may represent more than one fault. Use of a hand-held or PC based diagnostic tool will give a   brief   description   of   the   specific   fault,   narrowing   the area of troubleshooting. ECU Light Codes The     onboard     system     diagnostics     are     an     important feature  of  Eaton's  Central  Tire  Inflation  System.    For  a description of light fault displays see Operator Instructions section of this manual. Hand-Held Testers An  MPSI  hand-held  tester  may  be  used to   read   and   clear   service   codes   and   to obtain a short description of failures.  The tester    can    initiate    test    sequences    for controller    outputs    and    can    also    read system parameters. Personal Computer-Based Diagnostics Personal computer based software provides the capability   of   hand-held   testers   with   enhanced   display and data logging capability. A personal computer can display multiple parameters and provide more comprehensive descriptions of fault conditions. Use    of    a    personal    computer    requires    a    serial    link assembly  (industry  standard  SAE  J1587/1708)  such  as Kent-Moore's  part  number  J38351  and  Eaton's  Central Tire Inflation System diagnostic software. Diagnostic Connector Connection  of  a  Hand-Held  or  PC  based  diagnostic  tool is at the standard SAE J1587 connector. Test Modes Hand-held    or    PC    based    diagnostic    tools    allow    the system to be placed in several diagnostic modes: Monitor  (normal)  -   ECU   controls   tire   pressure,   while tool only monitors status. Inflate - System "manually" inflates (test for large leaks). Hold  -  Pressure  is  held  in  control  lines  (test  for  small leaks). Deflate  -   System   "manually"   deflates   (test   relief   valve pressure). Pressure   Check   and   Hold    -    System    checks    and displays  tire  pressures,  then  holds  pressure  in  air  lines (Quick test of control line and seal integrity). 3-92.16  Change 3