TM 10-3930-669-20 2-11.  GENERAL TROUBLESHOOTING INSTRUCTIONS (CONT). (c) Always turn the main power switch to the OFF position before connecting multimeter leads to a circuit unless instructed to do otherwise in the troubleshooting procedure 15. (d)  Connect  the  positive  (+)  multimeter  lead  to  the  circuit  being  tested.    Connect  the  negative  (-) multimeter lead to a known good ground. (e) Set main power switch to ON position and operate any other controls necessary to energize the circuit being tested. (f) Read the voltage value displayed on the multimeter. (g) Set the main power switch to the OFF position.  Return other controls to their "at rest" positions. (h) Disconnect multimeter leads from circuit. (i) Turn off multimeter. (3) General Relay Troubleshooting Procedure.  The following general relay troubleshooting procedure applies to most relays that are pushed into a receptacle and do not require any attaching hardware. (a)  Pull  relay  out  of  receptacle  just  enough  for  the  relay  terminals  to  make  contact  with  receptacle terminals.    Leave  about  1/4  to  3/8  in.  (6.35  to  9.53  mm)  space  between  the  relay  and  the  receptacle  to  insert  a multimeter lead and make contact with the terminal listed in the troubleshooting test. (b) Perform necessary test. (4)  General  Wiring  Harness  Short  Test.    The  following  procedure  applies  to  any  wiring  harness  suspected  of being shorted.  Refer to electrical schematics during this procedure. (a)  Connect  positive  (+)  multimeter  lead  to  multimeter  VOLT-OHM  connector.    Connect  negative  (-) multimeter lead to multimeter COM connector.  When the multimeter leads are separated or are measuring a circuit with no  continuity,  the  multimeter  will  indicate  "OL"  (Over  Limit)  on  its  display.  When  multimeter  leads  are  connected together, multimeter should display "0," indicating a continuous circuit with no (zero) resistance.  Wires in a harness that are not purposely joined or connected at a component should not have continuity (multimeter indicates "OL"). (b) Set multimeter function/range switch to the highest OHM range. (c) Disconnect harness connector. (d) Connect positive (+) multimeter lead to harness connector terminal of suspected wire. (e)  Connect  negative  (-)  multimeter  lead  to  each  of  the  remaining  harness  connector  terminals.  If multimeter  does  not  display  "OL,"  and  is  displaying  a  resistance  value  of  zero  or  higher,  this  indicates  a  continuous circuit.  Refer to the electrical schematic before repairing wires or replacing wiring harness to determine that the wires making a continuous circuit are not purposely joined or are not connected intentionally at a component. (f) Disconnect multimeter leads from connector. (g) Turn off multimeter. 2-12