4-9. GENERAL MAINTENANCE PROCEDURES -Continued
Electrical Components. This information pertains to the replacement of alarms, switches, relays, fuses,
solenoids, flasher units and sender units on the vehicle. Refer to the Electrical Wiring Diagrams,
Appendix H for locations of most of these components. Refer to para 4-95 and 4-96 for removal and
installation procedures for cab instrument panel switchs and lights.
To prevent damage to the electrical system components, always
disconnect the batteries before working on the electrical system.
A wire number is stamped on each end of the wires. This
number pertains to the wire numbers on the electrical wiring
diagrams in Appendix H.
Tag all wires before disconnecting.
Inspect wires for cut, burned, cracked or broken wire insulation. Repair by wrapping insulation
tape around damaged area or replacing damaged wires. Use an ohmmeter to check continuity of
wires. Refer to Electrical Wiring Diagrams, Appendix H.
Note the quantity, type, location and position of all mounting hardware before removal of
Refer to the illustrated Parts List in Appendix F for replacement parts.
Always use the same wire size and type when replacing wires.
If plastic cable ties or protective sleeves were removed to gain access to components or wires,
replace the ties or sleeves to protect wires from possible damage due to vehicle vibration or
Testing. Test operation of any system after installation or repair. Inspect for leaks, vibration, noise,
misalignment or other problems. Recheck after a few hours of normal operation.