P0218

Circuit Description
The Transmission Fluid Temperature (TFT) sensor is a thermistor that controls the signal voltage to the PCM. The PCM supplies a 5-volt reference to the sensor on circuit GRN/RED. When the transmission fluid is cold, the sensor resistance is high and the PCM will sense high signal voltage. As the fluid temperature warms to a normal transmission operating temperature of 100°C (212°F), the sensor resistance becomes less and the voltage decreases to 1.5 to 2.0 volts.
This DTC detects a high transmission temperature for a long period of time. This is a type "D" DTC.

Conditions For Setting The DTC
- No TFT DTCs P0712 or P0713.
- TFT is greater than 135°C (275°F).
- All conditions met for 21 seconds.

Action Taken When The DTC Sets
- Hot mode TCC Shift Pattern.
- The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
- ATF Lamp ON. (greater than 145°C (293°F))
- Disable E-side TCC OFF request.

Conditions For Clearing The DTC
- The DTC can be cleared from the PCM history by using a scan tool.
- The DTC will be cleared from history when the vehicle has achieved 40 warm-up cycles without a failure reported.
- The PCM will cancel the DTC default actions when the fault no longer exists and the ignition is cycled "oft" long enough to power down the PCM.

Diagnostic Aids
- Inspect the wiring for poor electrical connections at the PCM and at the transmission 16-way connector. Look for possible bent, backed out, deformed or damaged terminals. Check for weak terminal tension as well.
- Also check for a chafed wire that could short to bare metal or other wiring. Inspect for a broken wire inside the insulation.
- When diagnosing for a possible intermittent short or open condition, move the wiring harness while observing test equipment for a change.
- Check harness routing for a potential short to ground in circuit GRN/RED.
- Scan tool TFT sensor temperature should rise steadily to about 100° (212°F), then stabilize.
- Check for a "skewed" (mis-scaled) sensor by comparing the TFT sensor temperature to the ambient temperature after a vehicle cold soak. A "skewed" sensor can cause delayed garage shifts or TCC complaints.
- Check for a possible torque converter stator problem.
- Verify customer driving habits, trailer towing, etc.

Test Description
The numbers below refer to the step numbers on the diagnostic chart.
3. This test checks for a "skewed" sensor or shorted circuit.
4. This test simulates a TFT DTC P0713.





DTC P0218 Transmission Fluid Over Temperature