Lost Communication with ECM/PCM "A"
The ECM/PCM "A" has stopped transmitting on the vehicle data bus, so other control units no longer receive its messages. As this is the engine controller itself, the engine usually will not start or run while the message is missing. Typical causes are loss of power or ground at the module, an open or shorted CAN/LIN bus wire, a connector fault, or an internal module failure.
Affected components
- Ecm
- Can bus wiring
Common causes
- High likelihood: ECM unpowered (fuse, ground, supply wire)
- Medium likelihood: CAN wiring to ECM broken
- Low likelihood: ECM internally failed
Possible symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Diagnostic notes
- The malfunction indicator lamp may illuminate
- Reduced-power or limp mode may occur
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.