What it means
Voltage on shift fork C position sensor signal line is below the expected window. Wire shorted to ground or sensor short.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Shift fork C moves an internal transmission selector to engage its assigned gear range, and its position sensor reports that movement to the transmission control module (TCM). The TCM sets P283D when the fork C signal falls below the expected electrical range, which can make the fork's actual position unreadable.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
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 read TCM live data for shift fork C position to see when the signal went low and whether the fault is currently present.
- With the vehicle safely parked, inspect the fork C sensor connector and harness for corrosion, damaged insulation, pin damage, or contact with ground.
- Check the sensor's power and ground connections and measure the fork C signal against the manufacturer's specification.
- With power isolated as directed by the vehicle service information, check whether the fork C signal wire is shorted to ground.
- If wiring and connections pass, test the fork C position sensor for an internal short and replace it if it fails the manufacturer's test.
Common fixes
- Clean and secure corroded or loose fork C sensor connector pins.
- Repair a fork C signal wire shorted to ground or damaged harness section.
- Replace a fork C position sensor that tests internally shorted.
Can I keep driving?
Avoid driving if shifts are harsh, slipping, or the transmission is stuck in one gear; the TCM may be unable to confirm fork C engagement, and further gear changes could worsen transmission damage. If symptoms are absent, limit driving to a short trip for diagnosis.
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.