P0843
DTC P0843
Circuit Description
The TCC release switch is part of the transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body. The TCC release switch is normally-closed.
The switch signals the TCM that the TCC is released. This is accomplished by torque converter release fluid pressure acting on the switch contact which opens the circuit. When the circuit voltage is high, the TCM recognizes that the TCC is no longer engaged.
If the TCM determines that the TCC release switch is open indicating that the TCC is not applied and the TCC slip speed indicates that the TCC is applied, then DTC P0843 sets. DTC P0843 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0843 Transmission Fluid Pressure (TFP) Sensor Circuit High Voltage
Conditions for Running the DTC
^ No ISS DTC P0716 or P0717.
^ No TCC performance DTCs P0741 or P0742.
^ No TCC PWM solenoid valve electrical DTC P2763 or P2764.
^ The engine speed is greater than 500 RPM or 5 seconds.
^ The TCC is commanded ON.
^ The transmission fluid temperature is between 20°C (68°F) and 130°C (266°F).
^ The TCC slip speed is -20 to 60 RPM.
^ The engine torque is 50 Nm (37 ft. lbs.) or more.
Conditions for Setting the DTC
The TCC release pressure switch is open indicating release pressure is present for 6 seconds continuous twice during the same ignition cycle.
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 forces the TCC OFF.
^ The TCM inhibits TCC engagement.
^ The TCM inhibits 4th gear if the transmission is in Hot Mode.
^ The TCM freezes transmission adaptive functions.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
^ The TCM stores DTC P0843 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 after 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.
Diagnostic Aids
^ Do not replace the torque converter for this condition, refer to the Torque Converter Replacement Guide for other concerns. Torque Converter Replacement Guide
^ Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics
Test Description
The number below refers to the step number on the diagnostic table.
3. This step tests the TCMs ability to recognize a grounded circuit.
