P0218

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The Transmission Fluid Temperature (TFT) sensor is a thermistor within the Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch. The TFT sensor controls the signal voltage to the PCM. The PCM supplies a 5 volt reference to the sensor on circuit 1227.

When the transmission fluid is cold, the sensor resistance is high and the PCM senses high signal voltage. As the fluid temperature warms to a normal transmission operating temperature of 100°C (212°F), the sensor resistance reduces, and the voltage decreases to 1.5 - 2.0 volts.
If the PCM detects a high transmission temperature for a long period of time, then DTC P0218 sets. DTC P0218 is a type D DTC.

Conditions for Setting the DTC
- No TFT DTCs P0711, P0712 or P0713
- The TFT is greater than 130°C (266°F).
- All conditions met for 15 minutes (900 seconds).

Action Taken When the DTC Sets
- The PCM freezes shift adapts from being updated.
- The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the DTC
- A scan tool can clear the DTC from the PCM history The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
- The PCM cancels the DTC default actions when the fault no longer exists arid the ignition is OFF long enough in order to power down the PCM.

Diagnostic Aids
- Inspect the wiring for any poor electrical connections at the PCM. Inspect the wing at the Torque Converter Clutch (TCC) brake switch. Look for the following problems:

- A bent terminal
- A backed out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation

When diagnosing for all intermittent short or all open massage the wiring harness while watching the test equipment for changes.
- The scan tool should show the TFT sensor temperature rising steadily to about 100°C (212°F), then stabilize
- Check for a blocked or pinched transmission cooler line.
- Check for a blocked or damaged transmission cooler.
- Check for a torque converter stator problem. Verify the customer's driving habits, trailer towing, etc.
- Use the Temperature Vs Resistance scale in order to test the TFT sensor at various temperatures. Test the TFT sensor in order to eliminate the possibility of a skewed (mis-scaled) sensor. A skewed sensor could result in delayed garage shifts or TCC complaints.

Test Description

The numbers below refer to the step numbers on the diagnostic chart.
3. This step verifies that the sensor is not skewed (mis-scaled).This step also checks for a shorted circuit.
4. This step simulates a TFT DTC P0713.