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Home >> Jeep >> 2005 >> Wrangler Rubicon, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 570 (545RFE Automatic Transmission - Electrical Diagnostics) >> DTC Troubleshooting >> P0868-Line Pressure Low >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
  1. 1)  CHECK FOR RELATED DTC'S 

    With the scan tool, check for other transmission DTC's

    Is the DTC P0932 present also? 

    Yes 

    1. Refer to the Transmission category and perform the appropriate symptom.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  2).
  2. 2)  CONDITION P0868 PRESENT 

    With the scan tool, check the STARTS SINCE SET counter for P0868.

    NOTE: This counter only applies to the last DTC set.

    Is the START SINCE SET COUNTER 2 or less? 

    Yes 

    1. Go To step  3).

    No 

    1. Go To step  11).
  3. 3)  CHECK LINE PRESSURE SENSOR CONNECTION 

    Ignition on, engine not running. 

    With the scan tool, monitor the Line Pressure, firmly push the Line Pressure Sensor harness connector towards the Transmission.

    Did the Line Pressure change to about 207 kPa or 30 PSI when the connector was pushed? 

    Yes 

    1. Disconnect and properly reconnect the Line Pressure Sensor connector. Inspect terminals and repair as necessary.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  4).
  4. 4)  PCM AND WIRING 

    Turn the ignition off to the lock position.

    Remove the Starter Relay.

    NOTE: Removal of the Starter Relay is to prevent a Transmission, NO RESPONSE, condition and disable the starter.

    Install the Transmission Simulator, Miller tool #8333.

    With the Transmission Simulator select the "OFF" position on the "Input/Output Speed" switch.

    NOTE: Check connectors - Clean/repair as necessary.

    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.

    NOTE: All three scan tool Line Pressure readings should be steady and +/-14 kPa or 2.0 PSI of the reading specified on the Transmission Simulator.

    Did the Line Pressure read within +/-14 kPa or 2.0 PSI in all three positions? 

    Yes 

    1. Go To step  5).

    No 

    1. Go To step  7).
  5. 5)  LINE PRESSURE SENSOR 

    Turn 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 or 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 or 5 PSI of the scan tool reading? 

    Yes 

    1. Go To step  6).

    No 

    1. Replace the Line Pressure Sensor per the Service Information.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
  6. 6)  PLUGGED TRANSMISSION OIL FILTER 

    Turn 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.

    NOTE: 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? 

    Yes 

    1. Repair 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.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Repair 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.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
  7. 7)  (F856) 5-VOLT SUPPLY CIRCUIT SHORT TO VOLTAGE 
    Fig 1: Checking 5-Volt Supply Circuit for Short to Voltage
    GC0005158Courtesy of DAIMLERCHRYSLER CORP.

    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? 

    Yes 

    1. Repair the (F856) 5-volt Supply circuit for a short to voltage.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  8).
  8. 8)  (F856) 5-VOLT SUPPLY CIRCUIT OPEN 
    Fig 2: Checking 5-Volt Supply Circuit for Open
    GC0005156Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off to the lock position.

    Disconnect the PCM C1 harness connector and connect Miller tool #8815.

    CAUTION: 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 from the Line Pressure Sensor harness connector to the appropriate terminal of Miller tool #8815.

    Is the resistance above 5.0 ohms? 

    Yes 

    1. Repair the (F856) 5-volt Supply circuit for an open.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  9).
  9. 9)  (F856) 5-VOLT SUPPLY CIRCUIT SHORT TO GROUND 
    Fig 3: Checking 5-Volt Supply Circuit for Short to Ground
    GC0005157Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between ground and the (F856) 5-volt Supply circuit.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Repair the (F856) 5-volt Supply circuit for a short to ground.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  10).
  10. 10)  (T140) PRESSURE CONTROL SOLENOID CONTROL CIRCUIT SHORT TO ANOTHER CIRCUIT 
    Fig 4: Checking Pressure Control Solenoid Control Circuit for Short to Another Circuit
    GC0005159Courtesy of DAIMLERCHRYSLER CORP.

    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 (T140) 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 (T140) Pressure Control Solenoid Control circuit and any other circuit(s) in the Transmission Solenoid/TRS Assembly harness connector? 

    Yes 

    1. Repair the (T140) Pressure Control Solenoid Control circuit for a short to another circuit(s).
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Using 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.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
  11. 11)  INTERMITTENT WIRING AND CONNECTORS 

    The 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 EATX DTC EVENT DATA to help identify the conditions in which the DTC was set.

    Where there any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    No 

    1. Test Complete.