TM10-3930-660-20 8-47. MAIN WIRING HARNESS -  TEST/REPAIR/REPLACE This task covers: a. Testing b.  Repair c. Removal d. Installation Initial Setup Tools Materials/Parts Tool Kit, Automotive Mechanics Electrical Tape (App. C, Item 52) Tie Wrap (App. C, Item 53) Test  Equipment Ohmmeter Equipment  Condition Negative battery cable disconnected? para. 8-44 Failure of an electrical device to function is more likely due to a faulty switch (actuator), or to a faulty device itself, than to a broken wire in wiring harness. Do not assume that a broken wire exists until related electrical device and actuator have been checked. 1. INSPECT WIRES FOR POOR CONNECTIONS AT TERMINALS, CUTS OR OTHER DEFECTS. 2. CHECK CONTINUITY OF WIRES TO DETERMINE IF HIDDEN BREAKS EXIST. a. b. Use electrical schematic to trace path  of  wire. If possible, connect ohmmeter leads to ends of wire. 8-138