P1818

DTC P1818





Circuit Description with 4T40-E / 4T45-E Automatic Transaxle
The automatic transmission fluid pressure (TFP) manual valve position switch consists of three pressure switches. Two of the switches are normally-open, and determine gear range selection. The third switch is normally-closed, and detects torque converter clutch (TCC) release fluid pressure. The TFP manual valve position switch also contains the automatic transmission fluid temperature (TFT) sensor. These components are combined into one unit, attached to the control valve body.

The transmission control module (TCM) provides battery voltage on the two range signal circuits. By grounding one or more of the switches with fluid pressure from the manual shift valve, the TCM detects the selected gear range. When the transmission electrical connector is disconnected and the ignition is ON, the ground potential for the range signals from the TCM is removed, and an invalid gear range is indicated.

When the TCM detects a drive gear with a REVERSE ratio, DTC P1818 sets. DTC P1818 is a type B DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1818 Transmission Fluid Pressure (TFP) Valve Position Switch Indicates Drive without Drive Ratio

Conditions for Running the DTC
^ No TP DTCs P0122 or P0123.
^ No ISS DTCs P0716 or P0717.
^ No VSS DTCs P0722 or P0723.
^ No shift solenoid (SS) performance DTCs P0751, P0752, P0756, or P0757.
^ No SS electrical DTCs P0973, P0974, P0976, P0977.
^ No PSA DTCs P1810 or P1816.
^ The engine run time is greater than 5 seconds.
^ The TPS is 3 percent or greater.
^ The engine torque is greater than 20 Nm (15 ft. lbs.).
^ The output shaft speed is 50 RPM or more.
^ The TFT is greater than 0°C (32°F) when the TFP indicates drive.

Conditions for Setting the DTC
The TCM detects PARK, NEUTRAL, or a drive range with a REVERSE ratio for 2.8 seconds.

Action Taken When the DTC Sets
^ The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ The TCM commands maximum line pressure.
^ The TCM freezes transmission adaptive functions.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
^ The TCM stores DTC P1818 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC
^ The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the MIL/DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Test Description








The numbers below refer to the step numbers on the diagnostic table.
3. This step tests the indicated range signal to the manual valve range actually selected.
6. This step tests for correct voltage from the TCM.