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.
Automatic Transmission Input Speed (A/T ISS) Sensor Assembly (73)
The A/T ISS sensor operates identically to the A/T OSS sensor except it uses the stamped teeth on the forward and direct clutch housing assembly - with input shaft (567) as the rotor (reluctor). Remember that the forward and direct clutch housing assembly - with input shaft is driven at converter turbine speed. The A/T ISS sensor square wave form is also compared to a fixed clock signal internally within the TCM to determine actual converter turbine speed. The TCM uses transmission input and output speeds to help determine line pressure, transmission shift patterns, TCC apply pressure, gear ratios, and TCC slippage for diagnostic purposes.
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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.