Input/Turbine Speed Sensor Circuit No Signal

The input speed sensor on Nissan CVTs (JF011E/RE0F10A) loses signal due to metal debris on the sensor tip or wiring harness damage from heat. Remove the sensor from the bell housing, clean debris from the magnetic tip, and inspect the connector for corroded pins. If cleaning doesn't fix it, replace the sensor (Nissan 31935-1XF01). Also check CVT fluid level -- low fluid causes erratic sensor readings.

No-signal condition on GM 6L80E typically means the input speed sensor (ISS) has an open circuit. Located on the left side of the transmission, accessible from under the vehicle. Check the 2-pin connector for pushed-back pins first -- a common issue on trucks that do a lot of towing. Replace with AC Delco 24227792 if the connector is good but no signal is present. Clear codes and road test through all gears.

The 545RFE input speed sensor sits on the driver side of the transmission case near the bell housing. Signal loss is usually caused by a cracked sensor body or damaged wiring where the harness runs near the exhaust. Inspect for melted insulation first. Replace with Mopar 04800878AA. After replacement, perform a quick-learn procedure with a scan tool to reset adaptive shift pressures.

Honda automatics use a mainshaft speed sensor (countershaft speed sensor) for input speed. No-signal faults are often caused by internal transmission wiring harness deterioration -- the connector inside the case develops cracks. If the external sensor tests good (resistance 400-600 ohms), the internal harness likely needs replacement. This requires dropping the valve body. Check Honda TSB 15-058 for applicable models.