Transmission Controls

Diagnostic Chart:

Schematic:

Circuit Description with 4L60-E / 4L65-E Automatic Transmission
The flow of transmission fluid starts in the bottom pan and is drawn through the filter, control valve body assembly, transmission case and into the oil pump assembly. The oil pump assembly pressurizes the fluid and directs it to the pressure regulator valve where it becomes the main supply of fluid to the various components and hydraulic circuits in the transmission. Hot fluid exiting the torque converter flows through the converter clutch apply valve and into the transmission cooler lines to the oil cooler located in the vehicle radiator (and auxiliary cooler if equipped). From the cooler, fluid returns to cool and lubricate the front of the transmission. In forward drive ranges, D4 fluid from the manual valve is routed through an orificed cup plug in the rear of the transmission case to feed the rear lube fluid circuit.

When the Vehicle Control Module (VCM) detects a high Transmission Fluid Temperature (TFT) for a long period of time, then DTC P0218 sets. DTC P0218 is a type C DTC.

CONDITIONS FOR RUNNING THE DTC
^ No TFT sensor DTCs P0711, P0712 or P0713.
^ The ignition switch is in the RUN position for 5 seconds.

CONDITIONS FOR SETTING THE DTC
The TFT is greater than 130°C (266°F) for 600 seconds (10 minutes).

ACTION TAKEN WHEN THE DTC SETS
^ The VCM does not illuminate the Malfunction Indicator Lamp (MIL).
^ The VCM freezes shift adapts from being updated.
^ The VCM records the operating conditions when the Conditions for Setting the DTC are met. The VCM stores this information as Failure Records.
^ The VCM stores DTC P0218 in VCM history.

CONDITIONS FOR CLEARING THE DTC
^ A scan tool can clear the DTC.
^ The VCM clears the DTC from VCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
^ The VCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the VCM.

DIAGNOSTIC AIDS
^ The scan tool Trans. Fluid Temp. 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.
^ Refer to Symptom Diagnosis.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. This step checks for air flow restrictions or damage which may result in the transmission overheating.