Lost Communication with ECM/PCM "B"
The ECM/PCM "B" has stopped transmitting on the vehicle data bus, so other control units no longer receive its messages. A second engine/powertrain controller is unreachable, which can prevent the engine from running. 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: Secondary ECM unpowered
- Medium likelihood: CAN wiring to secondary ECM broken
- Low likelihood: Gateway module routing CAN messages incorrectly
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
- This code can affect emissions
- 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.