Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Description And Operation
DESCRIPTION
The Input Speed Sensor (ISS) and Output Speed Sensors (OSS) are two-wire magnetic pickup devices that generate Alternating Current (AC) signals as rotation occurs. They are mounted in the left side of the transmission case and are considered primary inputs to the Transmission Control Module (TCM).
OPERATION
The Input Speed Sensor provides information on how fast the input shaft is rotating. As the teeth of the input clutch hub pass by the sensor coil, an AC voltage is generated and sent to the TCM. The TCM interprets this information as input shaft RPM.
The Output Speed Sensor generates an AC signal in a similar fashion, though its coil is excited by rotation of the park gear teeth. The TCM interprets this information as output shaft RPM.
The TCM compares the input and output speed signals to determine the following:
- Transmission gear ratio
- Speed ratio error detection
- Content Validity Index (CVI) calculation
The TCM also compares the input speed signal and the engine speed signal to determine the following:
- Torque Converter Clutch (TCC) slippage
- Torque converter element speed ratio
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.