The input turbine speed sensor is usually mounted on the transmission case near the bellhousing, but the exact spot depends on the vehicle’s make and model. Some transmissions have a clearly visible external sensor, while others use an internal sensor or rely on other signals for input speed.
What the sensor does
The input turbine speed sensor (ISS) monitors the rotational speed of the transmission’s input shaft, which helps the vehicle’s TCM/ECU manage shifts, torque converter lockup, and overall transmission control. In some designs, the sensor is external; in others, the ISS may be internal or absent, with the system deriving input speed data from other sensors.
Where to look for it
Locations vary by design, but the following are common placements you may encounter on automatic transmissions. Use this as a guide and consult your service manual for a model-specific diagram.
- Front of the transmission case, near the bellhousing and torque converter input shaft.
- Side of the transmission case, near the extension housing and sometimes adjacent to oil cooler lines.
- Inside the transmission (internal sensor) behind a removable cover, valve body area, or pump/cover region—these are not always accessible without disassembling parts of the transmission.
Not all transmissions include an external input speed sensor. Some designs place the ISS internally or do not use a dedicated ISS at all; in those cases, the vehicle’s control module may rely on other sensors to estimate input speed.
How to locate it on your vehicle
- Identify your transmission model code or tag, which is usually found on the transmission near the bellhousing or in the service documentation for your vehicle.
- Check the factory service manual or a reliable repair guide for the exact location and connector type for your transmission model.
- Examine the exterior of the transmission case around the bellhousing and extension housing for a small 2- or 3-wire electrical connector.
- If no external sensor is visible, consult the manual about internal ISS locations or verify whether your model uses a different method to monitor input speed; avoid forcing components and seek professional assistance if needed.
Note: Handling transmission components can be delicate. When in doubt, refer to the official diagrams for your specific vehicle and consider professional service for inspection or replacement.
Safety and maintenance considerations
Always disconnect the battery and secure the vehicle before inspecting transmission components. If you are unfamiliar with transmission work, seek guidance from a trained technician to prevent damage or injury.
Summary
Location of the input turbine speed sensor varies by make and model. In many transmissions it sits on the outside of the case near the bellhousing or extension housing, but some designs use an internal sensor or do not include a dedicated ISS at all. To confirm the exact location for your vehicle, consult the factory service manual or a reputable repair guide for your specific transmission model.
What are the symptoms of a bad input turbine speed sensor?
Common symptoms include the vehicle entering fail-safe mode, abnormal transmission operation, and decreased fuel economy.
How to check turbine speed sensor?
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Can I drive a car with a P0715 code?
In some cases, you may not physically be able to drive with the P0715, P0716, P0717, and P0718 codes. Even if you physically can drive with these codes, you should only drive to your local retailer. It is not generally seen as safe to drive with these codes active for long periods of time.
Where is the input turbine speed sensor?
An input/turbine speed sensor is usually found behind the torque converter at the transmission input shaft. Start by inspecting the condition of the sensor as well as the wiring, connections and surrounding parts.