What it means
The clutch B actuator control circuit reports a control circuit/open condition. Clutch B engagement cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Clutch B's actuator engages or releases the B clutch in an automated transmission, and the TCM monitors its control circuit. This code sets when the circuit is open, so the module cannot reliably command Clutch B; a broken wire, open coil, or backed-out connector pin can interrupt the path.
Common causes
Most likely first.
- Open in actuator control wire
- Open actuator coil
- 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
- Save freeze-frame data and check live clutch commands to confirm whether the fault appears when the TCM tries to operate Clutch B.
- Inspect the Clutch B actuator connector for a backed-out pin, poor seating, corrosion, or damaged wiring.
- With the circuit safely isolated according to the manufacturer's procedure, check continuity through the control wiring and look for an open.
- Test the Clutch B actuator coil against the manufacturer's specification to determine whether it is internally open.
- If the coil and wiring test good, check the TCM-side connection and control output using the manufacturer's procedure.
Common fixes
- Reseat the connector and secure any backed-out Clutch B actuator pin.
- Repair an open or damaged section of actuator control wiring.
- Clean or replace damaged connector terminals to restore continuity.
- Replace the Clutch B actuator if its coil is confirmed open.
Can I keep driving?
Avoid driving if the transmission cannot engage reliably, slips, or loses drive; stop and arrange recovery if it will not select a usable gear. Clutch B may not respond to commands, which can cause missed shifts and further clutch damage.
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.