P1818

DTC P1818





Circuit Description
The automatic Transmission Fluid Pressure (TFP) manual valve position switch consists of 3 pressure switches. 2 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 2 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 you disconnect the transmission electrical connector and the ignition is ON, the ground potential for the range signals from the TCM will be removed, and an invalid gear range will be indicated. Refer to Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic.

When the TCM detects PARK, NEUTRAL or a drive range 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 MAP DTC's P0107 or P0108.
^ No TP DTC's P0120 or P0220.
^ No ISS DTC's P0716 or P0717.
^ No OSS DTC's P0722 or P0723.
^ No SS valve performance DTC's P0751, P0752, P0756, or P0757.
^ No SS valve electrical DTC's P0973, P0974, P0976, or P0977.
^ The engine is running for 5 seconds.
^ The TP angle is 3 percent or more.
^ The engine torque is greater than 20 Nm (15 ft. lbs.).
^ The output speed is 152.5 RPM or more.

Conditions for Setting the DTC
The TCM detects PARK/NEUTRAL or a drive range with a REVERSE ratio for 2.75 seconds.

Action Taken When the DTC Sets
^ The TCM requests the 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 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 TCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ 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.