What it means
The output stage for the clutch B BLDC motor cannot drive current through at least one of the U/V/W phases. Open wire or open winding.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Clutch B uses a brushless motor driven through U, V and W phase wires to operate the transmission clutch. The transmission control module monitors whether current can flow in those phases and sets this code when at least one path is open, so the motor cannot produce the commanded movement.
Common causes
Most likely first.
- Open phase wire
- Open motor winding
- Pin pushed back out of connector body
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and scan clutch B motor command and phase-related data to establish when the open-circuit fault occurs.
- Inspect the clutch B motor connector and U, V and W wiring for breaks, pulled or chafed sections, corrosion and loose connections.
- Check that each connector terminal is seated and grips its mating pin, paying particular attention to a terminal pushed back into the connector body.
- With power isolated according to the manufacturer's procedure, test continuity in each phase wire from the controller to the motor to locate an open.
- Measure the clutch B motor windings and compare the results with the manufacturer's specification to distinguish an open winding from a wiring fault.
Common fixes
- Reseat or repair a pushed-back or loose connector terminal.
- Repair a broken or corroded U, V or W phase wire.
- Replace the clutch B motor if a winding is open.
- Clear the fault and confirm the clutch B motor operates normally through the applicable scan-tool checks.
Can I keep driving?
Avoid driving if shifts are missing, harsh or slipping, or if the transmission is locked in one gear; the clutch B motor may not be able to control clutch engagement. If the vehicle remains driveable, keep the trip short and gentle, and stop if shifting becomes unpredictable.
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.