6L80-E Automatic Transmission

DTC P0218

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0218 Transmission Fluid Overtemperature

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

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 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 returns to the oil pan. The transmission fluid temperature (TFT) sensor is located in the control solenoid (w/body and TCM) valve assembly.

Conditions for Running the DTC
The TFT is -39 - 149°C (-38 - 300°F) for 5 seconds.

Conditions for Setting the DTC
The TFT is greater than 132°C (270°F) for 10 minutes.

Action Taken When the DTC Sets
^ DTC P0218 is a Type C DTC.
^ The 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 TFT reaches 132°C (270°F). The TFT on the scan tool should rise steadily to a normal operating temperature, and then stabilize. Ask about the customer's driving habits, trailer towing, etc. Trailer towing should occur in D4. Ensure the engine cooling system is functioning normally.

Reference Information

Schematic Reference

Connector End View Reference
^ Automatic Transmission Inline 16-Way Connector End View
^ Automatic Transmission Internal Connector End Views

DTC Type Reference
^ Diagnostic Trouble Code (DTC) Type Definitions
^ Diagnostic Trouble Code (DTC) List/Type

Electrical Information Reference
^ Circuit Testing
^ Connector Repairs
^ Testing for Intermittent Conditions and Poor Connections
^ Wiring Repairs

Special Tools Required
PSI Gage and Adapter?

Circuit/System Verification
1. Review the Failure Records when the DTC set.
2. If the engine coolant temperature (ECT) was above 125°C (257°F) when the DTC set, go to Engine Overheating and correct that concern first. Testing and Inspection
3. Perform the transmission fluid checking procedure. Refer to Transmission Fluid Checking Procedure. Procedures

Circuit/System Testing
1. Inspect the transmission cooling system for restrictions or damage.
2. Perform the automatic transmission oil cooler flushing and flow test. Refer to Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096). Component Tests and General Diagnostics
3. If a concern if found, repair or replace the damaged components as necessary.
4. Perform the automatic transmission line pressure checking procedure. Refer to Line Pressure Check Procedure.
5. If a concern if found repair or replace the damaged components as necessary.

Component Testing
Perform the transmission fluid leak diagnosis procedure. Refer to Fluid Leak Diagnosis.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

Repair or replace the automatic transmission cooler or lines as necessary.

Repair Verification
1. With a scan tool, clear the DTCs.
2. Operate the vehicle long enough to ensure the engine has reached normal operating temperature and the TFT has stabilized between 80-98°C (176-208°F)
3. Observe the specific DTC, and ensure DTC P0218 has run and passed.
4. Check for any other DTCs that you have not diagnosed.