Diesel Technician III

Unlimited Carrier Inc; Illinois; On-site; USD 52,000 - 59,000; Full time

Job summary

Unlimited Carrier Inc. is seeking a Diesel Technician III to diagnose and repair diesel trucks and equipment at our Illinois shop. This senior role requires expert problem-solving, leadership, and mentoring of junior technicians while ensuring high-quality repairs.

You will perform advanced diagnostics, service and replace major components, manage preventative maintenance, and document work in maintenance systems. A strong background with OEM software and electrical systems is essential.

Qualifications

• Minimum of 5 years of experience in diesel truck or heavy equipment repair.
• Advanced diagnostic skills using OEM software such as Cummins INSITE, Detroit DiagnosticLink, and Navistar Service Software.
• Strong understanding of electrical systems, aftertreatment systems, and vehicle data networks.
• Ability to read and interpret complex wiring diagrams, schematics, and service manuals.

Responsibilities

• Perform expert-level diagnostics on complex mechanical, electrical, aftertreatment, and driveline systems.
• Troubleshoot and repair diesel engines, aftertreatment and emissions systems, CAN bus, and driveline components.
• Conduct engine performance testing, calibrations, and software updates using OEM diagnostic tools.
• Perform engine component replacement and major assemblies such as transmissions, differentials, and axles.

Skills

Diesel truck repair

Diagnostics

Electrical systems

Wiring diagrams

Education

Formal diesel technology education or equivalent hands-on experience

Tools

Cummins INSITE

Detroit DiagnosticLink

Navistar Service Software

Job description

Job Description

Job Description

Job Title: Diesel Technician III
Department: Truck Service Point
Reports To: Shop Foreman
Effective Date: 08/04/2026

Position Overview

The Diesel Technician III is a highly skilled, senior-level technician responsible for performing complex diagnostics and advanced repairs on diesel-powered trucks and related equipment. This role serves as a technical expert within the shop, providing leadership, mentoring junior technicians, and ensuring high-quality repair standards.

Key Duties and ResponsibilitiesAdvanced Diagnostics & Repair

• Perform expert-level diagnostics on complex mechanical, electrical, aftertreatment, and driveline systems.
• Troubleshoot and repair:
  • Diesel engines
  • Aftertreatment and emissions systems (DPF, DOC, SCR)
  • Multiplexing and CAN bus systems
  • High-level electrical faults and communication issues
  • Transmission and driveline components
• Conduct engine performance testing, calibrations, and software updates using OEM diagnostic tools.

Major Component Repair

• Perform engine component replacement, including turbochargers, injectors, EGR systems, and pumps.
• Replace major assemblies such as transmissions, differentials, and axles.
• Execute advanced brake, suspension, and steering repairs.

Preventative Maintenance & Compliance

• Conduct and verify all levels of preventative maintenance (PM A, B, and C), including advanced inspection points.
• Perform DOT inspections and ensure full regulatory compliance.
• Identify root causes of recurring fleet issues and recommend corrective actions.

Leadership, Training & Technical Support

• Mentor and train Technicians I and II on best practices, troubleshooting, and repair procedures.
• Serve as a technical resource for complex job assignments.
• Support shop leadership in quality control initiatives.

Documentation & Reporting

• Document repairs, diagnostics, and parts usage accurately in maintenance systems.
• Contribute to procedural improvements and standard operating practices.

Safety & Shop Standards

• Lead by example in following all safety protocols and PPE requirements.
• Identify hazards and take corrective action to maintain a safe work environment.
• Ensure proper use and care of shop tools, equipment, and diagnostic devices.

Skills and RequirementsRequired

• Minimum of 5 years of experience in diesel truck or heavy equipment repair.
• Advanced diagnostic skills using OEM software such as Cummins INSITE, Detroit DiagnosticLink, and Navistar Service Software.
• Strong understanding of electrical systems, aftertreatment systems, and vehicle data networks.
• Ability to read and interpret complex wiring diagrams, schematics, and service manuals.
• Valid driver's license.
• Ability to lift 50+ pounds and perform physically demanding work.

Preferred Qualifications

• Formal diesel technology education or equivalent hands-on experience.
• Multiple ASE Medium/Heavy Truck (T-Series) certifications or ASE Master Certification.
• OEM-specific training or certifications (Cummins, Detroit, PACCAR, Navistar, Allison).
• Experience training or mentoring other technicians.
• Strong communication and leadership skills.
• CDL Class A or B license.

Work Environment

• Shop environment with exposure to noise, fumes, and heavy machinery.
• Requires standing, bending, lifting, and use of heavy tools.
• May require occasional outdoor work depending on facility setup.

Compensation

Pay Range: $38.00–$43.00 per hour, based on experience, certifications, and shift.

Schedule

• Monday–Friday, 10:00 AM – 6:30 PM

Additional Information

The information contained in this job description is intended to describe the general nature and level of work performed by associates within this classification. It is not intended to be, nor should it be interpreted as, a comprehensive inventory of all duties, responsibilities, or qualifications required of associates assigned to this position.