P1818

DTC P1818





Circuit Description
The automatic transmission fluid pressure (TFP) manual valve position switch consists of 3 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 powertrain control module (PCM) 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 PCM 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 PCM will be removed, and an invalid gear range will be indicated.
When the PCM detects a drive gear with a REVERSE ratio, DTC P1818 sets. DTC P1818 is a type B DTC.

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

Conditions for Running the DTC
^ No MAP DTCs P0107 or P0108.
^ No TP DTCs P0122 or P0123.
^ No VSS DTCs P0502 or P0503.
^ No ISS DTCs P0716 or P0717.
^ No SS valve performance DTCs P0751, P0752, P0756, or P0757.
^ No SS valve electrical DTCs P0753 or P0758.
^ The vehicle speed is 5 km/h (3 mph) or more.
^ The TP angle is greater than 10 percent.
^ The engine torque is greater than 34 Nm (25 ft. lbs.).

Conditions for Setting the DTC
The PCM detects a drive range with a REVERSE ratio for 5 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ The PCM elevates line pressure.
^ The PCM assumes a D4 shift pattern.
^ The PCM freezes transmission adaptive functions.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
^ The PCM stores DTC P1818 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC
^ The PCM 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 PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Test Description











These numbers 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 PCM.