Circuit/System Testing
- Start the engine and observe the Trans. Fluid Temp. parameter on the scan tool. Drive the vehicle while observing the Trans. Fluid Temp. parameter. The Trans. Fluid Temp. parameter should rise by 3°C (5°F).
- If the Trans. Fluid Temp. does not rise by 3°C (5°F), turn OFF the ignition.
- Disconnect the AT 20-way inline connector. Turn ON the ignition with the engine OFF. Observe the Trans. Fluid Temp. parameter on the scan tool. The Trans. Fluid Temp. should display -40°C (-40°F).
- If the Trans. Fluid Temp. is -40°C (-40°F), replace the TFT sensor.
- Using a DMM, measure the voltage on the TFT sensor signal circuit on the engine harness side of the AT 20-way inline connector and ground. The voltage should be near 5 volts.
- If the voltage is not near the specified value, repair the open or high resistance in the TFT sensor signal circuit.
- If an open or high resistance is not found, test the TCM.
- Measure the voltage between the TFT sensor signal circuit and the low reference circuit at the AT 20-way inline connector. The voltage should be near 5 volts.
- If the voltage is not near the specified value, repair the open or high resistance in the low reference circuit.
- Using the J 45681
jumper harness, measure the resistance between the TFT sensor signal circuit and the low reference circuit at the transmission side of the AT 20-way inline connector. Refer to Temperature Versus Resistance
for resistance values The resistance should be between the specified range for the given temperature.
- If the resistance is not within the specified range for the given temperature, replace the TFT sensor.