DTC P0218. GMC Truck Sierra Denali 2009

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2009 🢒 Sierra Denali 🢒 Transmission 🢒 Automatic Transmission - Allison 🢒 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

The transmission fluid temperature (TFT) sensor is a 2 wire sensor located in the pressure switch manifold (PSM). The transmission control module (TCM) supplies the TFT signal circuit and a low reference circuit. The resistance of the TFT sensor decreases as the oil temperature increases. The TCM monitors the voltage drop across the TFT sensor and calculates the temperature of the transmission fluid in the sump.

Conditions for Running the DTC

•	DTCs P0711, P0712, and P0713 are not active.

•	Engine speed is greater than 200 RPM for 5 seconds.

•	Ignition and battery voltage is between 9 and 18 V.

•	TFT is less than 150° C (302° F).

Conditions for Setting the DTC

This DTC sets when the transmission sump temperature is greater than 122°C (251°F) for 10 seconds.

Action Taken When the DTC Sets

•	The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).

•	The TCM changes the shift schedule to increase engine speed and improve cooler flow.

Conditions for Clearing the DTC

DTC P0218 is a Type C DTC.

Diagnostic Aids

•	Ask about the customer's driving habits, trailer towing, etc. Trailer towing should occur in tow haul mode.

•	Ensure the engine cooling system is functioning normally.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

•	Transmission General Description

•	Transmission Component and System Description

•	Electronic Component 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

Control Module References for scan tool information

Circuit/System Verification

Prior to cold start, ignition ON, observe the Trans. Fluid Temp. parameter with a scan tool. The Trans. Fluid Temp. parameter should be approximately the same as ambient temperature.
Inspect the transmission fluid level. Refer to Transmission Fluid Check.
Perform a road test while observing the Trans. Fluid Temp. parameter with a scan tool. The Trans. Fluid Temp. parameter should rise steadily to a normal operating temperature, and then stabilize. Refer to Road Test.
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed on the Freeze Frame/Failure Records data.