🚛 Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250)
Cummins engines power more than just Cummins-badged trucks — the ISX15/X15 and CM871/CM2350 ECM platforms show up as the spec’d engine option across Freightliner, Western Star, Peterbilt, Kenworth, and International chassis, alongside Cummins’ own ISL9 and ISB6.7 in medium-duty applications. Cummins ECM/ACM failures are common enough to have well-documented fault code signatures.
❓ What Do the ECM and ACM Control?
The ECM manages fuel injection, timing, and engine performance. The ACM (Aftertreatment Control Module) manages the DEF/SCR emissions system separately. Both report fault codes to the dash and diagnostic tools, and either can fail independently.
⚠️ Common Causes of Failure
- ✅ Power Supply Faults – unstable battery voltage or wiring issues are the leading cause behind Fault Code 1117 (Power Supply Lost With Ignition On), one of the most common CM871/CM2350 codes.
- ✅ Internal Microprocessor Failure – Fault Code 111 (ECM Microprocessor Internal Failure) indicates a critical internal fault requiring repair.
- ✅ Internal Hardware Failure – Fault Code 343 (ECM Internal Hardware Failure) means the truck should not be operated until the module is repaired.
- ✅ Wiring Harness and Connector Faults – often mistaken for ECM failure; should be ruled out before condemning the module.
- ✅ Heat and Vibration Fatigue – common on high-mileage highway tractors regardless of chassis brand.
⚠️ Symptoms of a Failed Module
- ✅ Fault codes 1117, 111, or 343 logged
- ✅ Heat-related engine shutdowns
- ✅ DEF/emissions-related derate or fault codes (e.g. 6254/6255/3712 on ISX/CM2350 engines)
- ✅ Poor engine performance or reduced power
- ✅ Difficulty starting or intermittent no-start
- ✅ Scan tool unable to communicate with the ECM or ACM
If you’re seeing any of the above, mail your module in for diagnosis — don’t pay for a full dealer replacement first.
💻 Our Repair Process
- ✅ Fault code retrieval and diagnostic review
- ✅ Bench testing to isolate ECM/ACM failure from wiring, power supply, or connector faults
- ✅ Component-level repair of damaged circuits and connectors
- ✅ Internal memory/data restoration where applicable
- ✅ Final bench validation before return
✅ Why Choose ECU Repair Doctor
- ✅ Component-level repair — cheaper and faster than a full ECM/ACM replacement
- ✅ Same-day/next-day turnaround on most units
- ✅ Mail-in service, anywhere in Canada
- ✅ Warrantied repair
- ✅ Serves independent shops and fleets, not just individual owners
🚗 Supported Models / Chassis
- ✅ Cummins ISX15 / X15
- ✅ Cummins ISL9
- ✅ Cummins ISB6.7
- ✅ Cummins-powered Freightliner, Western Star, Peterbilt, Kenworth, and International trucks
💻 Modules We Service
- ✅ Engine Control Module (ECM) – CM871 / CM2350 / CM2250
- ✅ ACM (Aftertreatment Control Module) / DEF Emissions Control Module
📞 Get a Quote
Call or text 647-784-9939, or see Contact for mail-in shipping instructions. Ship to 76 Sherry Road, Unit H, Scarborough, Ontario.
Sources referenced during research: truenorthdiesel.com Cummins ISX CM871 fault code guide, go-parts.com Cummins ISX ECM failure/fault code 1117 guide, scannerdanner.com CM2350 electronic controls reference, diesel-service-parts.com Cummins ISX fault codes list.