Custom Wiring Harness for Offroad and Performance Vehicles

Fastline Wiring and Fabrication builds professional custom wiring harnesses for offroad vehicles, race trucks, UTVs, rock crawlers, prerunners, and custom builds. Our wiring harnesses are built to handle harsh environments including heat, vibration, dust, and water exposure. Every harness is built clean, labeled, loomed, and designed to be reliable and easy to service.


Whether you need a complete vehicle rewire, accessory wiring, switch panel wiring, or troubleshooting, we build wiring systems you can depend on.

What We Offer

✔ Complete custom wiring harnesses

✔ Race truck wiring

✔ UTV wiring

✔ Jeep wiring

✔ Dual battery systems

✔ Fuse and relay panels

✔ Troubleshooting and rewiring

✔ Wiring repair and cleanup

✔ Accessory wiring

✔ ECU and engine wiring

Certified Wiring Expertise

HP High Performance Academy logo in black, white, and yellow with bold initials and ribbon banner

We are trained and certified by HP Academy in practical wiring and harness construction, ensuring clean, reliable, and professional electrical systems for every build.


✔ Clean Wiring

✔ Reliable Harness Construction

✔ Professional Electrical Systems


Built for Offroad Conditions

Offroad vehicles experience extreme vibration, dirt, mud, and heat. We use high-quality wiring, proper loom, sealed connectors, heat protection, and secure mounting to ensure your wiring system holds up in the toughest conditions.


Our wiring is built using professional motorsports wiring techniques to prevent electrical failures and make future service simple and organized.

We build custom wiring harnesses for:

⦿ Offroad Race Trucks

⦿ Prerunners

⦿ Rock Crawlers

⦿ UTVs

⦿ Jeeps

⦿ Overland Vehicles

⦿ Automotive Shops

⦿ Race Teams

⦿ Custom Truck Builders

Why Choose Fastline Wiring & Fabrication


  • Clean and organized wiring
  • Professional motorsports wiring methods
  • Built for offroad environments
  • Reliable and easy to service
  • Fast turnaround times
  • Serving Arizona offroad community

Custom Wiring Harness FAQs

  • What is a custom wiring harness?

    A custom wiring harness is a wiring system built specifically for your vehicle or project. It connects electrical components like lights, switches, batteries, relays, and accessories safely and cleanly.

  • Do you build wiring harnesses for off-road vehicles?

    Yes, we specialize in wiring harnesses for off-road vehicles, race vehicles, UTVs, sand rails, rock crawlers, and custom builds.

  • Can you rewire my entire vehicle?

    Yes, we specialize in off-road vehicles, race vehicles, custom builds, and project vehicles that need wiring, fabrication, or custom metal work.

  • Do you install switch panels and auxiliary lighting?

    Yes, we install switch panels, light bars, rock lights, whips, air compressors, radios, GPS units, and other 12V accessories.

  • Do you build plug-and-play wiring harnesses?

    Yes, we can build custom plug-and-play wiring harnesses to make installation simple and reliable.


  • How much does a custom wiring harness cost?

    Pricing depends on the size of the project, number of circuits, and components. Contact us for a quote based on your project.

  • How long does it take to build a custom wiring harness?

    Turnaround time depends on the complexity of the harness and the project. Contact us for current lead times.

  • Do you troubleshoot electrical problems?

    Yes, we diagnose and repair electrical issues, wiring problems, shorts, and accessory wiring.

  • What vehicles do you work on?

    We work on off-road vehicles, race vehicles, classic cars, trucks, UTVs, sand rails, and custom builds.

  • How do I get started?

    Use the contact form and tell us about your project. We can help design and build the wiring system you need.

  • Do customers need to buy parts through Fastline?

    No. Customers are welcome to provide their own switches, lights, panels, accessories, and electrical components for their build. Fastline Wiring & Fabrication guarantees the quality of the wiring installation itself, but cannot guarantee the performance or reliability of customer-supplied parts.

Contact Us

Need a custom wiring harness for your offroad vehicle or race build? Contact Fastline Wiring and Fabrication today to discuss your project.