Input Speed Sensor (ISS)

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Input Speed Sensor (ISS)

Courtesy of GENERAL MOTORS CORP.

The automatic transmission input speed sensor (ISS) is a magnetic inductive pickup that relays information about the transmission input speed to the TCM. The TCM uses this information to control the line pressure, TCC apply and release, and the transmission shift patterns. This information is also used to calculate the appropriate operating gear ratios and TCC slippage.

The ISS mounts on the transmission case under the channel plate next to the drive sprocket. An air gap of 0.26-2.90 mm (0.010-0.114 in) is maintained between the sensor and the teeth of the drive sprocket. The sensor consists of a permanent magnet surrounded by a coil of wire. As the drive sprocket is driven by the turbine shaft, an AC signal is induced in the ISS. Higher engine speeds induce a higher frequency and voltage measurement at the sensor.

Sensor resistance should be 625-725 ohms when measured at 20°C (68°F). Output voltage will vary with speed from a minimum of 0.5 volts AC at 550 RPM, to 200 volts AC at 7000 RPM.