P0717Powertrain
Powertrain · SAE
Input/Turbine Speed Sensor A Circuit No Signal
Meaning
The TCM receives no signal from the transmission input shaft or torque converter turbine speed sensor. The signal loss is complete and persistent. Without this information the TCM cannot determine input speed and cannot correctly execute its shift strategy.
Common causes
- Input/turbine speed sensor failed open-circuit
- Sensor connector unplugged or severely damaged
- Break in the sensor wiring harness (severed or broken wire)
- Reluctor ring missing, heavily damaged, or all teeth broken off
- Internal TCM fault preventing signal reception
Symptoms
- Malfunction indicator lamp (MIL) permanently illuminated
- Transmission locked in limp/fail-safe mode
- Gear shifts completely absent or severely restricted
- Vehicle operable only at reduced speed
- Possible illumination of the transmission warning indicator on the instrument cluster
Severity
Very high severity: total loss of the input speed signal makes the transmission ungovernable by the TCM; the vehicle is not safe to drive normally.
What to do
- Read fault codes and verify whether the input speed signal is zero or absent in live data
- Inspect the sensor connector for proper seating and absence of corrosion
- Check sensor circuit continuity with a multimeter (open-circuit test)
- Visually inspect the reluctor ring to confirm its presence and integrity
- Replace the sensor if open-circuit; repair the harness if broken; evaluate the TCM if all physical components are intact