Grand Cherokee 2WD L6-242 4.0L VIN S MFI (1993)
Transmission Temperature Sensor/Switch: Description and Operation
PURPOSE
Transmission fluid temperature readings are supplied to the Transmission Control Module (TCM) by the Thermistor. The temperature readings
are used to control engagement of the fourth gear overdrive clutch, the converter clutch, and governor pressure.
OPERATION
The TCM prevents engagement of the converter clutch and overdrive clutch when fluid temperature is below approximately 1 °C (30 °F).
If fluid temperature exceeds 126 °C (260 °F), the TCM will cause a 4-3 downshift and engage the converter clutch. Engagement is according to
the third gear converter clutch engagement schedule. The overdrive "OFF" lamp in the instrument panel also illuminates when the shift back to
third occurs. The transmission will not allow fourth gear operation until fluid temperature decreases to approximately 110 °C (230 °F).
