For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC P0218: Transmission Fluid Overtemperature

### Circuit/System 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. 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.

### Conditions for Running the DTC

The transmission fluid temperature is between -39 and +149°C (-38 and +300°F) for 5 seconds.

### Conditions for Setting the DTC

The transmission fluid temperature is greater than 132°C (266°F) for 10 minutes.

### Action Taken When the DTC Sets

• | DTC P0218 is a Type C DTC.

• | TRANSMISSION HOT - IDLE ENGINE displays on the driver information center (DIC).

• | The transmission control module (TCM) freezes transmission adaptive functions.

### Conditions for Clearing the DTC

DTC P0218 is a Type C DTC.

### Diagnostic Aids

The DIC, if equipped, will display TRANSMISSION HOT - IDLE ENGINE when the transmission fluid temperature reaches 132°C (270°F).

Ask the customer about possible overloading, exceeding the trailer towing limit, or towing in overdrive.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Transmission General Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Transmission Control Module Scan Tool Information

### Circuit/System Verification

Ensure that the transmission fluid level is at the proper level by performing the Transmission Fluid Check.

### Circuit/System Testing

1. Perform the Transmission Fluid Check.

⇒ | If the level is not within specifications, repair as necessary.

2. Inspect for the following conditions:

• | Transmission line pressure low--refer to Line Pressure Check.

• | Transmission fluid flow through cooler and/or auxiliary cooler, if equipped, is restricted due to:

- | Transmission fluid level low

- | A clogged filter

- | A leaking filter or seal--refer to Automatic Transmission Fluid and Filter Replacement.

• | A seized stator in the Torque Converter, refer to Torque Converter Diagnosis.

• | Air flow through transmission fluid cooler and/or auxiliary cooler, if equipped, is restricted due to:

- | Damaged fins

- | Debris

• | Engine overheating due to:

- | Low coolant level--check coolant temperature, coolant level, and hoses

- | Restricted air flow

- | Restricted coolant flow--refer to Engine Overheating

⇒ | If any of the conditions listed are found, repair as necessary

### Component Testing

• | Transmission Fluid Check

• | Line Pressure Check

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.