TM10-3930-660-20 8-46. CAB WIRING HARNESSES   -  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. The following procedures apply to cab main wiring harness, cab rear wiring harness and electric joystick controller wiring harness. TESTING 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 TERMINALS, CUTS OR OTHER DEFECTS. 2. CHECK WIRE CONTINUITY TO DETERMINE HIDDEN BREAKS EXIST. AT IF a. Use electrical schematic to trace path of wire. Refer to F/O-l. 8-131