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Understanding Mack Truck Air Compressors and Electrical Systems


Understanding Mack Truck Air Compressors and Electrical Systems

Understanding Mack Truck Air Compressors and Electrical Systems

For anyone interested in Mack trucks, particularly the intricate electrical systems and components like the air compressor, this article offers a comprehensive guide. We delve into the complexities of Mack Truck wiring, connectors, and the air compressor, highlighting key aspects and guidelines essential for body builders and technicians.

Mack Truck Air Compressor System

Installation and Maintenance

The air compressor in Mack trucks plays a crucial role, especially in braking systems. It’s vital to ensure proper routing of the compressor discharge line, adhering to guidelines such as support distances and avoiding sharp edges. Additionally, maintaining a consistent fall from the compressor to the air dryer is crucial to prevent line blockage.

Vehicle Control Unit (VECU) and Connectors

Introduced in Mack vehicles built on or after January 1, 2021, VECU5 is a critical component in managing the truck’s electronics. The VECU facilitates communication between different modules, ensuring seamless operation.

VECU Pin Layout

Understanding the pin layout is essential for troubleshooting and modifications. The VECU connects various functions like cruise control, brake pedal sensors, and power relays. Incorrect connections can lead to malfunctions or faults in the system.

Remote Operations and Auxiliary Systems

Remote start, stop, and engine stop systems offer convenience and safety. However, proper installation is necessary to avoid unintended consequences. For instance, the remote engine stop system requires specific relay and switch installations, adhering to Mack’s guidelines.

Bodybuilder Connectors and Schematic Examples

For third-party device installation, Mack Trucks provide an external connector for safe and efficient operation. Understanding the schematic examples for these connectors is crucial for body builders to ensure compatibility and functionality.

General Wiring Definitions and Guidelines

Terminology and Clipping Protocols

  • Abrasive Surface: Items capable of damaging routed commodities during operation.
  • AWG (American Wire Gauge): A standard for wire sizes.
  • Cable Tie: A nylon plastic strap, UV resistant, for bundling loads.
  • Chafing: Wear caused by rubbing.
  • High/Low Current Electrical Cables: Classification based on wire sizes.

Routing and Clipping Recommendations

Support DistancesElectrical cables should be supported every 18 inches (450 mm) and near connectors every 4 inches (100 mm).
Heat SpecificationsCables and hoses must be routed with specific distances from heat sources like the turbocharger.
Clipping GuidelinesClips should be designed to support the bundle without damaging the cables.


Mack trucks are renowned for their robustness and reliability. A clear understanding of their electrical systems, particularly the air compressor and VECU, is essential for effective operation and maintenance. By following Mack’s detailed guidelines and standards, technicians and body builders can ensure these vehicles continue to operate at their best.


1. What are Mack trucks used for?

Mack Trucks serve diverse roles in commercial industries. Their robust design and versatility make them ideal for highway transport, construction projects, garbage removal operations, and even military applications. Their durability and reliability are why they are a popular choice in these demanding fields.

2. Why is it called a Mack truck?

The name “Mack truck” originates from its founders, Augustus and Jack Mack, who initially ran a carriage company. They produced their first motorized vehicle in 1907. In 1922, the company underwent a name change from Mack Brothers Company to Mack Trucks, symbolizing its focus and specialization. Today, Mack stands as one of the leading manufacturers of medium-duty and heavy-duty trucks, known for their quality and endurance.

3. What is the function of the compressor in a truck’s air brake system?

The compressor in a truck’s air brake system is a critical component for maintaining the necessary air pressure levels. This ensures that the air brakes, along with other air-powered accessories, operate safely and effectively. Depending on the specific make and model of the heavy truck, the compressor can be either gear or belt-driven. Additionally, it can be cooled by air or an engine cooling system, varying with different truck configurations.

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Shaleen Ashish

Shaleen is a Journalism postgraduate, and like every other gen-z, loves a good dose of humor, Italian food, fashion trends, and TV series. She is an acomplished author and expert in the field of air compressors. Shaleen discovered her passion for technical products and gadgets early in life, which drove her research and write about it.

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