For a complete wiring diagram Refer to Section 8WLine pressure is measured by the Line Pressure Sensor (LPS) and regulation is achieved by changing the duty cycle of the Pressure Control Solenoid (PCS) controlled by the Transmission Control System. (5% duty cycle = solenoid off = Max line pressure, 62% duty cycle = solenoid on = Min line pressure). The Transmission Control System calculates the desired line pressure based on inputs from both the engine and transmission.The Transmission Control System calculates torque input to the transmission and uses it as the primary input to the desired line pressure calculation. This is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level 827 or 931kPa (120 or 135 psi) during shifts and in Park and Neutral to ensure consistent shift quality. The actual line pressure is continuously being compared to the desired (target) line pressure. If the actual line pressure is consistently lower than the target while driving, the line pressure low DTC P0868 will set. When Monitored:Continuously while driving in a forward gear.Set Condition:The PCM continuously monitors Actual Line Pressure and compares it to Desired Line Pressure. If the Actual Line Pressure is more than 15 psi below Desired Line Pressure for 3.5 seconds continuously will cause this DTC to set.Possible CausesCHECK FOR RELATED DTCSLOW FLUID LEVEL(F856) 5-VOLT SUPPLY CIRCUIT OPENPOOR LINE PRESSURE SENSOR CONNECTION(F856) 5-VOLT SUPPLY CIRCUIT SHORT TO GROUND(F856) 5-VOLT SUPPLY CIRCUIT SHORT TO VOLTAGE(T118) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT SHORT TO ANOTHER CIRCUITINTERNAL TRANSMISSIONLINE PRESSURE SENSORCRACKED, PLUGGED, OR MIS-INSTALLED PRIMARY OIL FILTERLOOSE COOLER RETURN SPIN ON FILTER (IF EQUIPPED)STUCK OR STICKING MAIN REGULATOR VALVEPOWERTRAIN CONTROL MODULEAlways perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) 1. CHECK FOR RELATED DTCSWith the scan tool, check for other transmission DTCs.Is the DTC P0932 present also?YesRefer to the Transmission category and perform the appropriate symptom.NoGo To 22. CHECK IF THE DTC IS CURRENTWith the scan tool, check the STARTS SINCE SET counter for P0868.This counter only applies to the last DTC set.Is the START SINCE SET COUNTER 2 or less?YesGo To 3NoGo To 113. CHECK THE LINE PRESSURE SENSOR CONNECTIONIgnition on, engine not running.With the scan tool, monitor the Line Pressure while firmly pushing the Transmission Line Pressure Sensor connector inwards towards the Transmission.Did the Line Pressure reading on the scan tool CHANGE to about 207 kPa (30 psi) or 0.7 volts when the connector was pushed inward?Yes (value was higher and changed to 207 kPa (30 psi) or 0.7 volts)Disconnect and properly reconnect the Line Pressure Sensor connector. Inspect terminals and repair as necessary.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) No (value is higher than 207 kPa (30 psi) or 0.7 volts and did not change or the value was already 207 kPa (30 psi) or 0.7 volts and did not change)Go To 44. CHECK THE PCM AND WIRINGTurn the ignition off to the lock position.Remove the Ignition Switch Feed fuse from the TIPM.Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear. The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in personal injury or death.Install the Transmission Simulator, Miller tool #8333.With the Transmission Simulator select the "OFF" position on the "Input/Output Speed" switch.Ignition on, engine not running.With the scan tool, monitor the Line Pressure during the following steps.Using the Transmission Simulator, set the rotary knob to each of the 3 line pressure positions.All three scan tool Line Pressure readings should be steady and ± 14 kPa (2.0 psi) of the reading specified on the Transmission Simulator.Did the Line Pressure read within ± 14 kPa (2.0 psi) in all three positions?YesGo To 5NoGo To 75. CHECK THE LINE PRESSURE SENSORTurn the ignition off to the lock position.Disconnect the Transmission Simulator, Miller tool #8333 and reconnect all previously disconnected connectors.Install the Line Pressure Adaptor, Miller tool #8259, and the Pressure Gauge, Miller tool #C-3293, 0 to 2000 kPa (0 to 300 psi).Start the engine in park.Monitor the line pressure readings of both the scan tool and the pressure gauge and compare the two readings.Is the line pressure gauge reading within 34 kPa (5 psi) of the scan tool reading?YesGo To 6NoReplace the Line Pressure Sensor per the Service Information.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) 6. CHECK FOR A PLUGGED TRANSMISSION OIL FILTERTurn the ignition off to the lock position.Remove and inspect the Transmission Oil Pan for excessive debris per the Service Information.Remove and inspect the Primary Oil Filter per the Service Information.Make sure the Primary Transmission Oil Filter and/or O-ring is not cracked or split.Does the Oil Pan contain excessive debris and/or is the Primary Oil Filter cracked or plugged?YesRepair the plugged, cracked, or split Primary Transmission Oil Filter and/or O-ring. If the Primary Transmission Oil Filter is plugged refer to the Service Information for the proper Hydraulic repair procedure.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoRepair internal transmission and inspect the Transmission Oil Pump per the Service Information and replace if necessary. If no problem is found, replace the Solenoid/TRS Assembly.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) 7. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE

Disconnect the Transmission Simulator, Miller tool #8333.Reconnect all previously disconnected connectors except the Line Pressure Sensor harness connector.Ignition on, engine not running.Measure the voltage of the (F856) 5-volt Supply circuit in the Line Pressure Sensor harness connector.Is the voltage above 5.5 volts?YesRepair the (F856) 5-volt Supply circuit for a short to voltage.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoGo To 88. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN

Turn the ignition off to the lock position.Disconnect the PCM C1 harness connector and connect Miller tool #8815.Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller tool #8815 to perform diagnosis.Measure the resistance of the (F856) 5-volt Supply circuit between the Line Pressure Sensor harness connector and the appropriate terminal of Miller tool #8815.Is the resistance above 5.0 ohms?YesRepair the (F856) 5-volt Supply circuit for an open.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoGo To 99. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between ground and the (F856) 5-volt Supply circuit.Is the resistance below 5.0 ohms?YesRepair the (F856) 5-volt Supply circuit for a short to ground.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoGo To 1010. CHECK THE (T118) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT

Turn the ignition off to the lock position.Disconnect the Transmission Solenoid/TRS Assembly harness connector.Disconnect all PCM harness connectors.Measure the resistance between the (T118) Pressure Control Solenoid Control circuit and all other circuits in the Transmission Solenoid/TRS Assembly harness connector.Is the resistance below 5.0 ohms between the (T118) Pressure Control Solenoid Control circuit and any other circuit(s) in the Transmission Solenoid/TRS Assembly harness connector?YesRepair the (T118) Pressure Control Solenoid Control circuit for a short to another circuit(s).Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoUsing the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the PCM per the Service Information. With the scan tool, perform QUICK LEARN.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) 11. INTERMITTENT WIRING AND CONNECTORSThe conditions necessary to set this DTC are not present at this time.Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.Wiggle the wires while checking for shorted and open circuits.With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.Where there any problems found?YesRepair as necessary.Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE) NoTest Complete.