P0841

VT25-E AUTOMATIC TRANSMISSION

DTC P0841





Circuit Description with VT25-E Automatic Transmission
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. The circuit may be functional, but not in the normal operating range. This diagnostic indicates poor sensor performance such as stuck, erratic, intermittent, or skewed values.

When the TCM detects an intermittent voltage or no voltage change in the TFP sensor circuit, then DTC P0841 sets. DTC P0841 is a type B code.

Conditions for Running the DTC
^ No HSCAN DTC U2105.
^ No engine speed DTC P0727.
^ No TFP sensor DTCs P0842, or P0843.
^ No line PC solenoid DTCs P0960, P0961, or P0962.
^ For condition 1 below, No OSS DTCs P0722, or P0723.
^ For condition 2 below, P0841 has not passed in the current ignition cycle.
^ The ignition voltage is 8 - 18 volts.
^ The engine speed is greater than 500 RPM for 5 seconds.
^ For condition 1 below, engine speed is 1,500 RPM or greater.
^ The transmission fluid temperature is 21°C (70°F) or greater.
^ For condition 1 below, output sensor speed is 300 RPM or greater.
^ For condition 2 below, commanded line pressure has changed more than 200 kPa (29 psi) since start-up.

Conditions for Setting the DTC
One of the following conditions occurs:

Condition 1
^ The magnitude of the commanded change in the line pressure is less 600 kPa (87 psi) or less.
^ The magnitude of the measured change in the line pressure is 1000 kPa (145 psi) or greater 10 times within 2 seconds.

Condition 2
The transmission fluid temperature has not changed by more than 100 kPa (15 psi) since start-up for 2 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 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 P0841 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.

Diagnostic Aids
^ If P0842, or P0843 is also set, diagnose the other DTC first.
^ Unsteady engine torque or engine misfires may cause fluctuation in transmission pressure and may set this code. Check the engine control module for fuel injector codes P0201 - P0204 and misfire codes P0300 - P030 4. If any of these DTCs are present, repair the condition which set the DTC first. Then clear DTCs and operate the vehicle within the conditions for running DTC P0841 as specified in this text.
^ 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.
^ A damaged filter, damaged or missing thrust washer or a leaking secondary pulley can cause DTC P0841 to set.