What is a CPC?
Common Powertrain Controllers are a relatively small computer module found on heavy duty trucks which have Detroit Diesel engines. It is responsible for the cab side of the engine control system, such as monitoring the throttle sensor, cruise control switches, dash panel gauges, brake switches and engine brake switches; it communicates these signals to the MCM (Motor Control Module), ACM (Aftertreatment Control Module) and TCM (Transmission Control Module) and also receives the information it needs from these modules. In conjunction with these modules it controls the engine, transmission and emission system.
What Trucks Use a CPC4 Module
Many Freightliner trucks have CPC Modules. Depending on the year and model of the truck you can find a CPC, CPC2, CPC3, CPC4 or CPC5. Specifically for CPC4 you can find them commonly on 2014-2019 Freightliner Cascadia, but also they are found on the Freightliner M2 and 122SD, and also on Oshkosh, Terex and Pierce trucks that have Detroit Diesel Engines.
Common symptoms of a defective CPC4:
The CPC4 module is an important component of a Detroit Diesel engine’s electronic control system. When the CPC4 module fails, it can cause a range of issues with the truck’s performance.
Some common symptoms of a bad CPC4 module include:
- Engine not starting: A failing CPC4 module can cause the engine to stall or shut down unexpectedly and not start again. Usually there will be no communication to the CPC module with a diagnostic tool.
- No throttle response: A bad CPC4 module may cause the engine to run at idle but have no throttle response. You will usually get throttle sensor failure codes when this happens.
- Check engine light: If the CPC4 module is malfunctioning, it can trigger the check engine light to come on with active codes for Internal Hardware Failure and Software Failure codes.
You can also call our Dallas office at 214-819-0517 or Tampa office at 813-724-4463 if you have any technical questions.
CPC Manual & Wiring Diagram
You can find an entire virtual manual for the CPC here: Link
CPC Location
The location of the CPC module can vary depending on the model of the truck. In general, the CPC4 module is located in the cab either behind the center panel of the dash or on the right side behind the glove compartment or cover.
If you need any assistance locating feel free to call us at our Dallas office at 214-819-0517 or Tampa office at 813-724-4463
CPC4 Fault Codes
The CPC4 can generate various fault codes when it detects an issue with the engine’s performance. Some common CPC4 module fault codes seen when the CPC is damaged include:
| 609 | 12 | CPC2 Hardware Failure |
| 609 | 13 | CPC Software Diagnostics |
| 609 | 16 | Internal temperature of CPC4 too high. |
| 625 | 2 | PTCAN Incorrect MCM System ID Received |
| 628 | 2 | EEPROM Checksum Failure |
| 628 | 12 | EEPROM Checksum Failure for the SCR Block |
| 628 | 14 | XFLASH Static Fault Code Memory Page Read Write Failure |
| 629 | 2 | CPC Hardware/Software Mismatch |
| 629 | 12 | DDEC Data Xflash Write Error. Replace CPC. |
Is it possible to repair my CPC4?
Yes, it is possible to repair CPC4 modules. At Truck ECM we can diagnose and repair CPC4 modules usually within 1-2 days.
We specialize in heavy duty diesel engine control modules to provide the best quality and speed of service to get you back on the road quickly!
If you suspect that your CPC4 module is malfunctioning, call us at our Dallas office at 214-819-0517 or Tampa office at 813-724-4463.