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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.

24 of 56 Items
  • Paccar Peterbilt 379 DDEC3 Engine Harness

    Paccar

    Peterbilt 379 DDEC3 Engine Harness

    The Peterbilt 379 DDEC3 Engine Harness from Paccar is a genuine Paccar 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.Peterbilt Engine Harness DDEC 3 Peterbilt...

    $1,227.52
  • Cummins ISX 15 Injector Wiring Harness

    Cummins

    ISX 15 Injector Wiring Harness

    The ISX 15 Injector Wiring Harness from Cummins is a genuine Cummins 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.ISX15 Injector Wiring...

    $291.99
  • Williams Controls TPS Harness

    Williams

    Williams Controls TPS Harness

    The Williams Controls TPS Harness from Williams is a genuine Williams heavy-duty truck part you can count on. Built to the standards heavy-duty truckers count on — dependable, durable, and ready to work.Williams Controls Throttle Position Sensor...

    $28.72
  • Freightliner Chassis Jumper Harness - RH

    Freightliner

    Chassis Jumper Harness - RH

    The Chassis Jumper Harness - RH from Freightliner is a genuine Freightliner heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Main Chassis Jumper Harness - RHFitment: Confirm this part...

    $46.75
  • Freightliner Chassis Jumper Harness - LH

    Freightliner

    Chassis Jumper Harness - LH

    The Chassis Jumper Harness - LH from Freightliner is a genuine Freightliner heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Main Chassis Jumper HarnessFitment: Confirm this part fits...

    $46.75
  • Newstar Speed Sensor Wiring Harness Newstar Speed Sensor Wiring Harness

    Newstar

    Speed Sensor Wiring Harness

    The Speed Sensor Wiring Harness from Newstar is a genuine Newstar heavy-duty truck part you can count on. Built to the standards heavy-duty truckers count on — dependable, durable, and ready to work.Speed Sensor Adapter HarnessFitment: Confirm this part...

    $43.26
  • Paccar Peterbilt DDECIII Cab Harness

    Paccar

    Peterbilt DDECIII Cab Harness

    The Peterbilt DDECIII Cab Harness from Paccar is a genuine Paccar heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Fitment: Confirm this part fits your truck's make, model, and year...

    $1,195.14
  • Paccar 60 Series Harness - Peterbilt

    Paccar

    60 Series Harness - Peterbilt

    The 60 Series Harness - Peterbilt 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.Engine Harness Firewall to ECM Peterbilt...

    $1,336.61
  • Detroit Diesel Detroit Injector  Harness

    Detroit Diesel

    Detroit Injector Harness

    The Detroit Injector Harness from Detroit Diesel is a genuine Detroit Diesel 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.Detroit 60 Series Injector Harness...

    $409.99
  • TQI Radiator Ground

    TQI

    Radiator Ground

    The Radiator Ground 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 year before...

    $125.00
  • TQI Kenworth Dash Harness - Detroit TQI Kenworth Dash Harness - Detroit TQI Kenworth Dash Harness - Detroit

    TQI

    Kenworth Dash Harness - Detroit

    The Kenworth Dash Harness - Detroit from TQI is a genuine TQI heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Fitment: Confirm this part fits your truck's make, model, and year...

    $186.75
  • TQI

    Peterbilt Alternator Cables - CAT

    The Peterbilt Alternator Cables - CAT from TQI is a genuine TQI heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Fitment: Confirm this part fits your truck's make, model, and year...

    $260.00
  • TQI Peterbilt Alternator Cables, Detroit TQI Peterbilt Alternator Cables, Detroit

    TQI

    Peterbilt Alternator Cables, Detroit

    The Peterbilt Alternator Cables, Detroit from TQI is a genuine TQI heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Fitment: Confirm this part fits your truck's make, model, and year...

    $205.00
  • TQI Peterbilt 579 ECM Power Harness - CAT

    TQI

    Peterbilt 579 ECM Power Harness - CAT

    The Peterbilt 579 ECM Power Harness - CAT 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.ECM Power Harness Glider Application CAT in Peterbilt...

    $175.00
  • TQI

    Peterbilt 579 Cab Harness - CAT 40 Pin

    The Peterbilt 579 Cab Harness - CAT 40 Pin from TQI is a genuine TQI heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Cab Harness, ECM to Firewall CAT 40 Pin in a Peterbilt 579 Glider...

    $1,380.00
  • Freightliner CAT 70 Pin Harness - Coronado

    Freightliner

    CAT 70 Pin Harness - Coronado

    The CAT 70 Pin Harness - Coronado from Freightliner is a genuine Freightliner heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Fitment: Confirm this part fits your truck's make,...

    $483.59
  • Detroit Diesel Detroit ECM

    Detroit Diesel

    Detroit ECM

    The Detroit ECM 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.Fitment: Confirm this part...

    $1,959.79
  • Detroit Diesel Engine Sensor Harness

    Detroit Diesel

    Engine Sensor Harness

    The Engine Sensor 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.Engine Sensor...

    $428.92
  • Freightliner Cab Harness - Coronado

    Freightliner

    Cab Harness - Coronado

    The Cab Harness - Coronado from Freightliner is a genuine Freightliner heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Cab/Engine Harness Detroit 60 Series in FreightlinerFitment:...

    $782.03
  • TQI Peterbilt Communication Harness Detroit

    TQI

    Peterbilt Communication Harness Detroit

    The Peterbilt Communication Harness Detroit from TQI is a genuine TQI heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.Fitment: Confirm this part fits your truck's make, model, and...

    $35.00
  • Freightliner RH Headlight Harness - Coronado

    Freightliner

    RH Headlight Harness - Coronado

    The RH Headlight Harness - Coronado from Freightliner is a genuine Freightliner heavy-duty truck part you can count on. Designed to keep you seen and safe, with a bright, sharp appearance that stands out day or night.RH Headlight Harness Freightliner...

    $332.49
  • TQI Kenworth CAT 6NZ Cab Harness

    TQI

    Kenworth CAT 6NZ Cab Harness

    The Kenworth CAT 6NZ Cab Harness from TQI is a genuine TQI heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.TQI Cab Harness-KW CAT 6NZ CAB HARNESS -#1102-8011Fitment: Confirm this...

    $977.50
  • Trux Accessories 3 Prong Pigtail for Marker Lights

    Trux Accessories

    3 Prong Pigtail for Marker Lights

    The 3 Prong Pigtail for Marker Lights from Trux Accessories is a genuine Trux Accessories heavy-duty truck part you can count on. Bright, durable, and built to give your truck a finished, custom look.3 PRONG PIG TAIL FOR MARKER LIGHTSFits: Marker Lights...

    $2.15
  • Paccar 60 Series Transducer Harness

    Paccar

    60 Series Transducer Harness

    The 60 Series Transducer Harness from Paccar is a genuine Paccar heavy-duty truck part you can count on. A quality heavy-duty truck part built to keep you running and looking your best.60 Series Transducer Harness Fits both Peterbilt and Kenworth...

    $112.02
24 of 56 Items