Cummins QSB3.9, QSB4.5, QSB5.9 CM55X (VP30) Wiring Diagram - Bulletin 4021399

This wiring reference for the Cummins QSB3.9, QSB4.5, QSB5.9 CM55X (VP30) helps you follow circuits, connectors and harnesses when you are diagnosing an electrical problem or checking a repair.

Document reference: 3990517.

What the diagrams cover

• Full engine wiring schematic
• ECM connector views and pinouts
• VP30 pump wiring
• Sensor wiring

Models covered

• QSB3.9
• QSB4.5
• QSB5.9 (CM55X
• VP30)

User help

1. Check the fit first. Compare your model and serial number with the coverage shown above. If you are unsure, message us with those details before ordering and we will help you confirm.
2. Get the file. This is a digital PDF download. Nothing is shipped, so you can start using it as soon as you have the file.
3. Open it anywhere. Use any current PDF reader (Adobe Acrobat Reader, your browser, or a phone or tablet app). Save a copy to your computer and to a backup drive.
4. Jump straight to the section you need. Start from the table of contents or search for a part name, fault code or value, then print just those pages for the workshop.
5. Trace circuits methodically. Identify the circuit, connector or harness in the diagram, then check voltage, continuity and grounds at the points shown before replacing components.
6. Stay safe. Repairs on engines, hydraulics, fuel and electrical systems can be dangerous. Follow the safety instructions in the document, use proper tools and support equipment, and follow local regulations.

Cummins and all model names are trademarks of their respective owners and are used here only to identify compatibility. This store is an independent seller and is not affiliated with or endorsed by Cummins. For informational and maintenance use.