New Free Resource: Downloadable Wiring Diagrams Now Available on DefyDiagnostics.com
At Defy Diagnostics, we know how frustrating it can be when you’re chasing down an electrical fault, and you don’t have the right diagram in front of you. Whether you’re troubleshooting a Cummins injector circuit, tracing a Paccar communication line, or verifying voltage on a Detroit Diesel aftertreatment system, wiring information is the backbone of a proper diagnostic process.
That’s why we’re excited to announce a brand-new addition to our Resources section:
Free Wiring Diagrams Available Now
We’ve launched a growing library of diesel engine wiring diagrams, completely free to access. These are high-quality, easy-to-read diagrams compiled to support technicians, fleet managers, and independent shops who work on today’s complex systems.
Current Coverage Includes:
- Cummins (ISX, X15, ISB, ISL and more)
- Detroit Diesel (DD13, DD15, DD16)
- Caterpillar (C7, C9, C12, C15)
- Paccar (MX-11, MX-13)
- Navistar / International (MaxxForce, A26)
- Isuzu (N-Series, F-Series)
- Mack / Volvo
- Allison transmission harness diagrams
- …and more being added weekly!
Each diagram is verified, clearly labeled, and formatted for fast reference. Whether you’re diagnosing power loss, communication errors, or injector faults, these diagrams can save you valuable time and help prevent costly misdiagnoses.
A Resource Built for Technicians, by Technicians
We’ve spent years in the field ourselves, and we know how critical accurate information is when every minute of downtime matters. That’s why this wiring diagram library isn’t behind a paywall or subscription, it’s part of our commitment to supporting the diagnostic community and giving professionals the tools they need to succeed.
Need a Specific Diagram? Request It!
If you don’t see what you’re looking for, just head to our Wiring Diagram Request Form on the site. You can submit a request for a specific engine, model, or system, and we’ll do our best to send it by email or update the site within 24 hours.
Your feedback directly shapes what we add next, whether that’s an aftertreatment harness for a Cummins ISX15, a CAN network layout for a Paccar MX-13, or a DEF system schematic for a Volvo D13.
Check It Out
Visit the new section now:
Wiring Diagrams – Free Resources | Defy Diagnostics
Bookmark it, share it with your team, and check back often, we’ll be expanding coverage across diesel, off-highway, and marine applications soon.
Defy Diagnostics is proud to power the professionals who keep fleets moving. From TEXA diagnostic tools and Konfort A/C machines to training resources and support, our goal is to make advanced diagnostics easier, faster, and more accessible for everyone.
