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Wiring Harnesses

Semi-Truck Wiring Harnesses: OEM & Aftermarket Solutions

When electrical problems sideline a rig, nothing matters more than getting the right parts fast. At Fitzgerald Truck Parts, we stock wiring harnesses for trucks that are built to keep heavy-duty equipment running strong mile after mile. From daily drivers to specialty builds, our inventory is designed for real-world demands, real shop conditions, and real uptime expectations.

We carry harnesses for all major systems, including engine, ECM, injector, cab, chassis, and sensor applications. Our selection covers both OEM and high-quality aftermarket options, giving you flexibility based on budget, availability, and application. Every wiring harness we sell is selected with durability and performance in mind, helping reduce electrical failures that can shut down a job and drain revenue.

Our inventory supports a wide range of manufacturers, including Paccar brands like Peterbilt and Kenworth, along with Cummins, Detroit Diesel, Freightliner, Williams, and TQI. Fitment matters in heavy-duty repair, which is why we focus on application-specific harnesses designed around exact engine platforms and truck models, not guesswork.

Harnesses for Engine, ECM, and Injector Systems

Engine-side electrical issues demand fast, reliable fixes. We keep critical injector and ECM harnesses in stock to support common repairs and full system replacements. Popular options include Cummins ISX 15 injector harnesses and Detroit injector harnesses trusted by shops across the country.

For engine control and communication, we stock ECM and cab or chassis harnesses that connect vital electrical components across the truck. This includes Peterbilt DDECIII cab harnesses and Freightliner and Coronado configurations used in fleet and owner-operator applications.

We also specialize in glider kits and engine swaps. TQI harnesses are purpose-built for conversions like installing CAT or Detroit engines into newer Peterbilt platforms such as the 579. These harnesses are designed to handle complex routing, proper signal communication, and long-term durability under load.

Smaller sensor harnesses matter just as much. Throttle position sensor harnesses, speed sensor harnesses, and other signal-critical connections are available to handle the fine details that keep a modern vehicle operating correctly.

Fast Shipping & Reliable Returns

Downtime costs money. That’s why we offer same-day shipping on all in-stock harness orders placed before 3:00 PM CST. With us, orders ship quickly so your truck spends less time in the bay and more time earning.

We ship throughout the lower 48 states using UPS Ground for packages under 130 pounds. Every order is packed with care to protect connectors, terminals, and every wire path inside the harness.

If a part is not correct, unused and uninstalled items can be returned within 30 days of purchase in original packaging. Shipping costs are the customer’s responsibility. All parts include the original manufacturer warranty, giving added confidence when ordering.

Wiring Harness FAQs

How do I confirm correct fitment?
Match the part number and brand to your truck’s VIN and engine details. Our experienced parts team is available by phone to help verify compatibility before ordering.

Are these harnesses new or used?
All harnesses listed are new unless clearly stated otherwise. We focus on reliable, long-lasting products built for demanding environments.

What is the TQI brand?
TQI – or Truck Quality International – produces heavy-duty harnesses commonly used in glider kits. These harnesses are known for strong construction and accurate electronic integration.

What price range do you offer?
We stock items ranging from small pigtails priced just a few dollars to complete cab harnesses exceeding $1,300. This wide range supports quick fixes, full rebuilds, and everything in between.

  • Detroit Diesel Engine Harness

    Detroit Diesel

    Engine Harness

    The Engine Harness from Detroit Diesel is a genuine Detroit Diesel heavy-duty truck part you can count on. Engineered for the demands of heavy-duty diesel powertrains, it's built to deliver dependable performance mile after mile.Detroit Engine Harness 60...

    $491.94
  • Paccar Peterbilt Distribution Center-2 Fuse Paccar Peterbilt Distribution Center-2 Fuse

    Paccar

    Peterbilt Distribution Center-2 Fuse

    The Peterbilt Distribution Center-2 Fuse from Paccar is a genuine Paccar heavy-duty truck part you can count on. Engineered for the demands of heavy-duty diesel powertrains, it's built to deliver dependable performance mile after mile.Peterbilt...

    $205.34
  • Freightliner Fuel Gauge  Harness

    Freightliner

    Fuel Gauge Harness

    The Fuel Gauge Harness from Freightliner is a genuine Freightliner heavy-duty truck part you can count on. Built to keep your diesel running strong through the daily grind of over-the-road and vocational work.Fitment: Confirm this part fits your truck's...

    $26.89
  • Peterbilt 579 Overlay Harness

    Peterbilt 579 Overlay Harness

    The Peterbilt 579 Overlay Harness from Fitzgerald Truck Parts is a heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.PETE 579 OVERLAY HARNESSFitment: Confirm this part fits your...

    $190.00
  • TQI Engine Harness Detroit

    TQI

    Engine Harness Detroit

    The Engine Harness Detroit from TQI is a genuine TQI heavy-duty truck part you can count on. Built to keep your diesel running strong through the daily grind of over-the-road and vocational work.Harness Engine Detroit #1102-8009 Detroit 60 Series 12.7L...

    $400.00
  • TQI Peterbilt 579 Harness W/D60 Engine

    TQI

    Peterbilt 579 Harness W/D60 Engine

    The Peterbilt 579 Harness W/D60 Engine from TQI is a genuine TQI heavy-duty truck part you can count on. Engineered for the demands of heavy-duty diesel powertrains, it's built to deliver dependable performance mile after mile.Fitment: Confirm this part...

    $1,065.00
  • TQI Chasis Node Ground, Peterbilt

    TQI

    Chasis Node Ground, Peterbilt

    The Chasis Node Ground, Peterbilt from TQI is a genuine TQI heavy-duty truck part you can count on. Built to the standards heavy-duty truckers count on — dependable, durable, and ready to work.Fitment: Confirm this part fits your truck's make, model, and...

    $85.50
  • Paccar ECM Power Harness, Peterbilt  CAT

    Paccar

    ECM Power Harness, Peterbilt CAT

    The ECM Power Harness, Peterbilt CAT from Paccar is a genuine Paccar heavy-duty truck part you can count on. Built to the standards heavy-duty truckers count on — dependable, durable, and ready to work.ECM Power Harness, PeterbiltFitment: Confirm this...

    $483.32