What it means
The vehicle bus reports loss of communication with drive motor control module B. Torque commands for the second EV/hybrid traction motor cannot be coordinated, forcing the powertrain into a degraded mode.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
Drive motor control module B manages torque commands and status for the second electric or hybrid traction motor. This code sets when other powertrain modules stop receiving expected messages from module B, preventing coordinated torque control and potentially forcing reduced-power operation.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
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
How to diagnose it
- Scan all modules for freeze-frame data and related hybrid, inverter or network faults; determine whether only drive motor control module B or several modules are offline.
- Check the dashboard for hybrid or EV warnings and note whether propulsion is reduced, since module B's missing messages can affect the second traction motor.
- Inspect the module B connector and accessible harness for damage, corrosion, moisture or signs of impact, without opening high-voltage components.
- Have the specified low-voltage power and ground to module B checked, then test its network wiring for opens, shorts or poor connections using manufacturer procedures.
- If power, ground and network wiring are sound, use manufacturer diagnostics to assess module B and its gateway; high-voltage system work should be performed by qualified personnel.
Common fixes
- Repair a loose, damaged or corroded low-voltage connector serving module B.
- Repair an open or short in the network wiring to the second drive motor control module.
- Restore the module's specified low-voltage power or ground by correcting the identified supply fault.
- Repair a confirmed gateway or network routing fault that blocks module B messages.
- Replace module B only after wiring and supplies test correctly and manufacturer diagnostics identify it as faulty.
Can I keep driving?
Avoid driving if propulsion is reduced, unpredictable or unavailable; arrange recovery if the vehicle cannot maintain safe traffic speed. Even if it still moves, limit the trip to a safe place because further loss of motor coordination can reduce power or leave the vehicle unable to move.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.