P0843

DTC P0843

Circuit Description
The transmission fluid pressure (TFP) sensor is used to monitor the line pressure and feedback to the transmission control module (TCM) with an analog signal of 0-5 volts. The pressure sensor is fed with tier 2 feed fluid pressure and nominally ranges from 483-5861 kPa (70-850 psi). This diagnostic monitors the TFP circuit.

When the TCM detects a voltage signal that is excessively high, DTC P0843 sets. DTC P0843 is a type A code.

Conditions for Running the DTC
- No line PC solenoid DTCs P0960, P0961, P0962.
- The engine speed is greater than 500 RPM for 5seconds,
- The commanded line pressure is 4000 kPa (580 psi) or less.

Conditions for Setting the DTC
The TCM detects a measured line pressure value of 4500 kPa (653 psi) or greater for 20 seconds.

Action Taken When the DTC Sets
- The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
- The TCM commands a line pressure increase for all operating conditions.
- The TCM freezes main line pressure 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 P0843 in TCM history.

Conditions for Clearing the MILJDTC
- 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.

Diagnostic Aids
- To locate an intermittent problem, use the scan tool to monitor Line Pressure Actual with the engine running. Wiggle the wiring harness from the TCM to the transmission while watching for a change in the parameter. This may help locate the area where the fault in the wiring may lie. Also, check for poor terminal connections.
- Inspect the connectors at the TCM, the transmission, and all other circuit connecting points for an intermittent condition.
- Inspect the circuit wiring for an intermittent condition.

Steps 1 - 9:

Steps 10 - 14:

DTC P0843