through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the
speed of the vehicle increases. Output voltage varies with speed from a minimum of 0.5 volts at
100 RPM to more than 100 volts at 8,000 RPM. The TCM converts the pulsing voltage to vehicle
speed. The TCM uses the vehicle speed signal to determine shift timing and torque converter
clutch (TCC) scheduling.
Automatic Transmission Fluid Temperature Sensor
The automatic transmission fluid temperature (TFT) sensor is part of the automatic transmission
fluid pressure (TFP) manual valve position switch. The TFT sensor is a resistor, or thermistor,
which changes value based on temperature. The sensor has a negative-temperature coefficient.
This means that as the temperature increases, the resistance decreases and as the temperature
decreases, the resistance increases.
The transmission control module (TCM) supplies a 5-volt reference signal to the TFT sensor and
measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance
is high and the TCM detects high signal voltage. As the fluid temperature warms to a normal
operating temperature, the resistance becomes less and the signal voltage decreases. Refer to
Transmission Fluid Temperature Sensor Specifications for a complete comparison of sensor
resistance, temperature and signal voltage.
The TCM uses the TFT sensor information to control shift quality and torque converter clutch
(TCC) application.
Transmission Range Switch
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado