Circuit Description
The primary source of heat in the transmission is the torque converter. Hot oil exits the torque converter through the torque converter clutch (TCC) control valve and flows to the transmission cooler supply line. The supply line connects to the cooler, which is located in the radiator. From the cooler, the oil returns through the oil cooler return line and enters the lubrication circuits. After lubricating the internal components, the oil then returns to the oil pan. The oil pump draws oil through the filter from the oil pan, where the transmission fluid temperature (TFT) sensor is located. Oil is also drawn in the from adapter case bottom pan. The oil pump pressurizes the oil and directs it to the pressure regulator valve. The pressure regulator valve is the starting point for the main supply of oil to the torque converter and the transmission hydraulic components.
When the transmission control module (TCM) detects high transmission oil temperature for an extended period of time, DTC P0218 sets. DTC P0218 is a type C DTC.
Condition for Running the DTC
The ignition is ON.
Condition for Setting the DTC
The TFT is greater than 165°C (329°F) for 19.9 seconds.
Action Taken When the DTC Sets
| • | The TCM does not flash the sport mode lamp. |
| • | The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM switches to a default transmission fluid temperature of 130°C (266°F). |
| • | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM records this information as Failure Records. |
| • | The TCM stores DTC P0218 in TCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the fault no longer exists. |
Diagnostic Aids
| • | The TFT displayed on the scan tool should rise steadily to a normal operating temperature, then stabilize. |
| • | Ask about the customer's driving habits, trailer towing, etc. Trailer towing should occur in D3. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission ? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission | |
2 |
Important: Record the Failure Records before clearing the DTC. Using the Clear Info function erases the Failure Records from the ECM and the TCM. Was the engine coolant temperature above the specified value when the DTC set? | 125°C (257°F) | Go to Engine Overheating in Engine Cooling | |
3 |
Is the action complete? | -- | -- | |
4 |
Did you find and correct a condition? | -- | ||
5 |
Did you find and correct a condition? | -- | ||
6 |
Did you find and correct a condition? | -- | -- | |
7 | Perform the following procedure in order to verify the repair:
Does the TFT remain below 165°C (329°F)? | -- | System OK |
