Control Module Communication Bus "B" Off
A control module has shut its bus B interface off because the bus is non-functional. Bus B is typically a secondary CAN segment (often body or chassis) and a failure disables all modules connected to it.
Affected components
- Can bus wiring
- Can terminating resistor
- Control module
Common causes
- High likelihood: Bus B line shorted to supply or ground
- Medium likelihood: One failing module pulling the bus down
- 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
- 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.