GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Avalanche - 4WD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC P0218

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

Diagnostic Fault Information

Component

Cause

DTCs

Engine
    • Engine coolant level low
    • Incorrect engine coolant
    • Old coolant or incorrect concentration level
    • Cooling system leak
    • Radiator hose kinked or pinched
    • Loose, missing, or damaged radiator air seals or deflector - restricted air flow
    • The radiator and A/C condenser has air flow obstructions to include large amount of bent fins
    • The cooling fans do not operate
    • Inspect the engine mechanical for worn, leaking, cracked cylinder heads, or engine block

P1258

Transmission

Vehicle Overload or Beyond Capacity Towing:

    • Vehicle is overloaded
    • Vehicle is towing beyond capacity
    • Towing in wrong gear
    • Vehicle modifications

P0218

Heat transfer:

    • Engine overheating
    • Cooler restrictions - radiator has restricted flow/blockage
    • Restricted air flow
    • Vehicle modifications
    • Aftermarket auxiliary cooler installed incorrectly, incorrect flow direction -- reversed flow
    • Restricted, blocked, or pinched transmission cooler lines.
    • Stuck open or stuck closed transmission cooler line thermostat

P0218

Transmission Abuse:

    • Engine overheating
    • Excessive brake torque maneuvers
    • Vehicle overloaded
    • Vehicle is towing beyond capacity
    • Vehicle modifications

P0218

Vehicle Damage:

    • Damage to vehicle under carriage
    • Transmission bottom pan damage
    • Restricted air flow

P0218

Transmission Fluid:

    • Fluid leaks
    • Low fluid level
    • Contaminated or poor transmission fluid quality

P0218

Low Fluid Pump Output:

    • Low fluid level
    • Blocked, damaged or loose filter
    • Pinched or restricted cooler lines
    • Restricted cooler - damage or debris
    • Inefficient pump - worn

P0218

Clutch Slippage:

    • Low fluid level
    • Low Fluid Pump Output
       - Damaged or leaking clutch seals
       - Internal hydraulic leak
       - Worn clutch plate assembly

P079A

P079B

P079C

P079D

Circuit/System Description

The primary source of heat in the transmission is the drive motor generators. The drive motor generators are cooled by the transmission fluid. Hot fluid exits the drive motor generators and flows to the transmission cooler supply line. The supply line connects to the cooler, which is in front of the radiator. The transmission fluid cooler pipe assembly is equipped with an internal thermostat that opens at 80°C (176°F) for optimum transmission operation and fuel economy. The transmission cooler pipe thermostat is part of the transmission fluid cooler pipe assembly, located near the transmission and is not serviced separately. From the cooler, the fluid returns through the transmission fluid cooler pipe assembly and enters the lubrication circuits. After lubricating the internal components, the fluid returns to the oil pan. The transmission fluid temperature (TFT) sensor is located in the control solenoid (w/body and TCM) valve assembly and is not serviced separately.

Conditions for Running the DTC

The TFT is -50 and +150°C (-58 and +302°F) for 5 seconds.

Conditions for Setting the DTC

The TFT is greater than 135°C (275°F) for 10 seconds.

Action Taken When the DTC Sets
    • P0218 is a Type B DTC.
    • The TCM freezes transmission adaptive functions.

Conditions for Clearing the DTC

P0218 is a Type B DTC.

Diagnostic Aids

The driver information center (DIC), if equipped, will display 'TRANSMISSION HOT- Idle Engine' when the TFT reaches 132°C (270°F). The TFT parameter 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. Ensure the engine cooling system is functioning normally.

Reference Information

Schematic Reference

Hydraulic Schematics

    •  Park - Engine Running
    •  EVT Mode Reverse - Engine Running
    •  Neutral - Engine Running
    •  EVT Mode Low - Engine Running
    •  EVT Mode Low - Engine Off
    •  Drive Range, First Gear
    •  Drive Range, Second Gear
    •  Drive Range, Third Gear
    •  Drive Range - Fourth Gear
    •  EVT Mode High - From Drive Range 4th Gear
    •  Power Off Low Default
    •  Power Off High Default
    •  Fluid Passages

Connector End View Reference

Component Connector End Views

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

Special Tools

J 24731 Tempil Stick

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, refer to Engine Overheating and correct that concern first.
  2. Perform the transmission fluid checking procedure. Refer to Transmission Fluid Check .

Circuit/System Testing
  1. Inspect the transmission cooling system for restrictions or damage.
    2. ⇒If a concern is found, repair or replace the restricted or damaged components as necessary.
  2. Perform the Transmission Fluid Cooler Flushing and Flow Test .
    3. ⇒If a concern is found, repair or replace the damaged components as necessary.
  3. Perform the automatic transmission Line Pressure Check procedure.
    4. ⇒If a concern is found repair or replace the damaged components as necessary.
  4. Inspect the transmission cooler line thermostat for a stuck closed condition.
    5. ⇒If a concern is found repair or replace the damaged components as necessary.

Component Testing
    • Perform the Fluid Leak Diagnosis .
    • Perform the Transmission Fluid Check procedure.
    • Perform the Line Pressure Check procedure.
    • Perform the Main Fluid Pump Pressure High or Low procedure.
    • With a hand held infra red thermometer or J 24731 , test for the transmission cooler supply line thermostat opening at 80°C (176°F). The transmission cooler supply line temperature should be higher on the transmission side of the thermostat than the cooler side until 80°C (176°F) is reached.
       ⇒If the thermostat tests stuck open or closed, replace the transmission cooler supply line assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Repair or replace the automatic transmission cooler or lines as necessary. Refer to Transmission Fluid Cooler Pipe Replacement .

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.