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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 52 (Automatic Transaxle Diagnosis - 4T65-E) >> Diagnostic Tests >> DTC P0717: Input Speed Sensor Circuit No Signal >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2002 Buick Regal, 2002 Buick Century, 2001 Buick Regal, and 2001 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

The Input Shaft Speed (ISS) sensor is a permanent magnet with a coil of wire wound around it. The ISS sensor mounts in the case cover facing the reluctor wheel of the input shaft. As the reluctor wheel is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.

There is a fixed air gap between the sensor and the teeth on the sensor reluctor wheel. The ISS sensor input is used by the PCM to control line pressure, TCC apply and release, and transaxle shift patterns. This sensor is also used to calculate the gear ratios and TCC slippage.

If the PCM detects a low input speed while the vehicle and engine speeds are high, then DTC P0717 sets. DTC P0717 is a type "B" DTC.