3500 4x4 Pickup V10-488 8.0L Magnum (1994)
Transmission Temperature Sensor/Switch: Description and Operation
DESCRIPTION
The transmission temperature sensor is a variable, thermistor type. It reacts to temperature changes. At cold transmission oil temperatures, its
resistance is high. As temperatures increase, its resistance will decrease.
The transmission temperature sensor is used on models equipped with an automatic transmission and a factory installed transmission
cooler. It is also used on models equipped with certain heavy-duty options and an automatic transmission (8.0L V-10 / 5.9L turbo diesel
with 47RH transmission).
Transmission Temperature Sensor
LOCATION
The transmission temperature sensor is located in the transmission cooler outlet line, next to the transmission.
Transmission Temperature Warning Lamp
An instrument panel-mounted transmission temperature warning lamp is also used.
PURPOSE
Its purpose is to help control transmission fluid overheating.
NOTE: Fourth gear and converter clutch operation in the 47RH are normally controlled by the PCM, but are also controlled by the temperature
sensor under certain conditions.
OPERATION
The temperature sensor constantly monitors transmission fluid temperature. The sensor is in circuit with overdrive and converter clutch solenoid
through the Powertrain Control Module (PCM).
The temperature sensor prevents overdrive and converter clutch engagement when fluid temperature is below 60 °F for the overdrive clutch; and
below 70 °F for the converter clutch.
If the fluid temperature indicator lamp comes on, fluid temperature is either at, or above 285°F. This indicates an approaching overheat condition.
The sensor will downshift the transmission to third gear and possibly disengage the converter clutch. At this point, it will be necessary to
