Cummins QSL9 CM850 Electronic Control System Troubleshooting and Repair Manual

This manual covers one engine with one controller: the Cummins QSL9 with the CM850 control module.

It includes fault code diagnosis and symptom-based troubleshooting, CM850 ECM pinouts and sensor circuits, diagnostic steps for the fuel system, sensors and actuators, component tests, and wiring and connector repair. Because it covers just this engine, every procedure applies to yours, which saves time compared with a multi-engine manual.

What the manual covers

• Fault code diagnosis and symptom-based troubleshooting
• CM850 ECM pinouts and sensor circuits
• Fuel system, sensor and actuator diagnostics
• Wiring and connector repair
• Component testing

Compatibility

• Models: QSL9 with CM850
• Engine: 8.9 L inline six
• Control module: CM850
• Manual type: Electronic control system troubleshooting and repair

Before you buy

Check the label on your ECM. A QSL9 with a different control module needs a different manual.

Your engine's dataplate shows the engine model, the engine serial number (ESN) and the CPL number. Compare those with the models above. If you're not sure, email us the dataplate details and we'll check for you.

File format

Digital download, delivered as a ZIP file. Unzip it before opening. Opens on a computer, tablet or phone.

We're an independent seller and are not affiliated with or endorsed by Cummins. Brand and model names are used only to identify the engines this manual covers.