1. CAB, CHASSIS, AND TRAILER WIRING SYSTEMS

2. SUB-SYSTEMS l Main Cab Harness Receives power from Batteries Has Fuses and Circuit Breakers Feeds power to other truck harnesses Extends to cab/front lighting on some cab designs Some fuse panels identified well

3. SUB-SYSTEMS l Engine Harness Supplies power to starter motor, alternator, Jacob engine brake, preheating/starting system, fan clutch, shutterstats and heating and air conditioning system Supplies power to Chassis Harness on some trucks

4. SUB-SYSTEMS l Chassis Harness Supplies power to all frame mounted electrical and electronic components such as; lighting anti-skid brakes fuel tank level gauge trailer coupling connector

5. SUB-SYSTEMS l Trailer Harness Supplies power to lighting on the trailer(s)

6. WIRING STANDARDS l American Manufactuers follow SAE and TMC/ATA standards l Wiring diagram supplied with every truck (affixed or pouch) l Circuit identification is standard l Wiring Colors l Standard nomenclature or abbreviations

7. Electrical Maps l Wiring Diagram Grid Reference System Pages identified by model of truck l Circuit Diagram Shows how components are connected together without detail Specifies location of wiring and components

8. CIRCUIT IDENTIFICATION l Two Methods Color and Number Circuit Number and Circuit Name l Letters and Numbers can be printed on wiring every 4 inches l Wiring can be tagged FIG 5-3

9. HARNESS STANDARDS l WIRE CONDUCTORS ANNEALED COPPER WIRE l WIRE INSULATION SXL - Standard duty thermosetting cross-linked polyethylene Wiring temp must not exceed 100 degree F If higher temp, must be protected

10. OTHER HARNESS STANDARDS l Voltage drop not more than 0.5V l Must be supported at least every 18 inches l Wiring Harness Coverings l Wiring should be located so that rocks, road debris, etc will not harm it.