P1812

P1812 WITH 4 SPEED AUTOMATIC

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The transmission fluid pump is constantly circulating fluid through the torque converter. Hot fluid leaving the converter flows through the transmission cooler lines to the oil cooler, located in the vehicle radiator. From the cooler, the fluid returns to the transmission. Lube 1 fluid flows through the input shaft to lubricate the transmission components in the front of the transmission. The Lube 2 fluid circuit is fed by line pressure at the pressure regulator valve. Lube 2 fluid flows through the oil feed pipes, and into the forward clutch support. Lube 2 fluid provides lubrication to the rear components of the transmission.

When the Powertrain Control Module (PCM) detects a high transmission fluid temperature (TFT) for a long period of time, then DTC P1812 sets. DTC P1812 is a type D DTC.

CONDITIONS FOR SETTING THE DTC

^ The transmission fluid temperature is greater than 130°C (260°F) for 15 minutes.

^ No TFT Sensor DTCs P0712 or P0713.

ACTION TAKEN WHEN THE DTC SETS

^ The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

^ The PCM freezes shift adapts from being updated.

^ DTC P1812 is stored in the PCM history.

CONDITIONS FOR CLEARING THE DTC

^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS

Ask the customer about overloading the vehicle, exceeding the trailer-towing limit, or towing in Overdrive.

TEST DESCRIPTION

The numbers below refer to the Step numbers on the diagnostic table.

2. This Step tests for low fluid level, which can cause high transmission fluid temperatures.

3. This Step inspects for transmission cooling restrictions.