CDL Combination Vehicles TestInspecting Combination VehiclesMedium
A driver is performing a pre-trip inspection of a combination vehicle. They notice that the electric cord (pigtail) connecting the tractor to the trailer is chafed and has exposed wires. What is the primary risk associated with this condition?
- AIntermittent or complete loss of trailer lights and ABS function.
- BIncreased fuel consumption due to electrical resistance.
- CReduced air pressure to the trailer's braking system.
- DOverheating of the tractor's engine cooling system.
Show answer & explanationAnswer & explanation
Correct answer: A. Intermittent or complete loss of trailer lights and ABS function.
The electric cord (pigtail) carries all electrical signals between the tractor and trailer, including power for lights and the Anti-lock Braking System (ABS). Chafed and exposed wires can lead to short circuits, open circuits, or poor connections, resulting in the loss of these critical functions, which are essential for safety and compliance.
Why the other options are wrong
- B. While electrical issues can indirectly affect efficiency, the primary and immediate risk is loss of critical safety systems, not fuel consumption.
- C. The pigtail carries electrical signals, not air pressure. Air lines handle the braking system's air.
- D. The pigtail is unrelated to the engine cooling system.
Trailer Electrical Cord (Pigtail)
The multi-conductor electrical cable connecting the tractor's electrical system to the trailer's, supplying power for lights, ABS, and other electrical components.
- Transmits all electrical signals.
- Damage can cause light failures or ABS malfunction.
- Must be free of chafing, cuts, and corrosion.
Memory trick: Pigtail perfect, lights are bright!