TM 10-3930-675-20-1 0012 00-5 ELECTRONIC CONTROL UNIT (ECU) INPUT VOLTAGE TROUBLESHOOTING - CONTINUED 0012 00 Table 3. Error Code 123 - 10V Reference Voltage for Servo ECU (790) Failure Troubleshooting Procedures - Continued. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Error Code 123 - 10V Reference Voltage for Servo ECU (790) Failure - Continued 6.  Enter “DIAG SERVO 1 (13)” menu  and  check  voltage  of 10V    REF    OUT.    Voltage should be 9.3-10.4V. a. If  voltage  is  present,  replace servo  ECU  (790)  (WP  0079 00). b.If voltage is not present, notify SRA. a.  If voltage is correct, connect    connector    X157 and continue with troubleshooting pro- cedure. b.  If voltage is not as specified, disconnect connector  on  joystick.  If voltage  is  in  range  after disconnecting joystick connector, replace joystick (WP 0081 00). c.  If voltage is not as specified, check continuity between joystick pin 3 and connector   X155   pin   15, between   joystick   pin   10 and   connector   X155   pin 13, between joystick pin 9 and   connector   X155   pin 12,  and  between  joystick pin 2 and connector X155 pin 14. a. If continuity is present, notify SRA to replace wire. b.If  continuity  is  not  present, notify SRA. 7.  Remove cover from junction box  X169,  located  on  right side    of    boom.    Disconnect boom   extension   and   angle sensors   from   junction   box X169 pins 2 and 3. 8.  Enter “DIAG SERVO 1 (13)” menu  and  check  voltage  of 10V    REF    OUT.    Voltage should be 9.3-10.4V. a.  If voltage is correct, check boom angle and extension sensor wires. Replace    sensor    if    wires    are damaged (WP 0098 00 and WP 0099 00).