What it means
The output driver for shift fork B actuator reports current or junction temperature above its protection threshold. Stalled actuator or short-circuit fault.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The TCM's output driver supplies current to the shift fork B actuator and monitors its electrical load and its own temperature. This code sets when driver current or temperature exceeds its protection threshold, which can happen if the actuator circuit is shorted or fork B is jammed and the actuator stalls.
Common causes
Most likely first.
- Short to ground in actuator wiring
- Shift fork mechanically jammed — actuator stalls
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 transmission codes and freeze-frame data, then check live data for fork B commands, actuator status, and whether the fault appears during a shift.
- With the vehicle safely switched off as specified by the manufacturer, inspect the fork B actuator connector and wiring for chafing, pin damage, corrosion, or contact with ground.
- Check the fork B actuator circuit for a short to ground using the manufacturer's wiring diagram and test procedure.
- If wiring is sound, use the specified scan-tool tests to compare commanded fork B movement with its reported position or response.
- If electrical checks pass but the actuator stalls, have fork B and its mechanism checked for binding before replacing the actuator or TCM driver.
Common fixes
- Repair chafed or shorted wiring to the shift fork B actuator.
- Clean or repair damaged terminals at the fork B actuator connector.
- Correct a mechanical jam or binding in shift fork B.
- Replace a failed fork B actuator if testing confirms it is faulty.
- Repair or replace the TCM only if its output driver is confirmed faulty after circuit and actuator checks.
Can I keep driving?
Because this fault can trigger limp mode or leave the transmission in one gear, avoid driving if shifts are missing, slipping, or unpredictable; arrange recovery if the vehicle cannot select gears reliably. Continued operation can worsen transmission 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.