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Home >> Jeep >> 2020 >> Grand Cherokee Trackhawk >> Repair and Diagnosis >> External Pages >> Different car >> Section 272 (68RFE Automatic Transmission - DTCS P0218-00 To P0871-00 - 2500HD & 3500HD) >> DTC Troubleshooting >> P0846-00-2C Pressure Switch Rationality >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2019 RAM 3500 HD and 2019 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. DETERMINE IF RELATED TCM POWER INPUT DTCS ARE SET 
    1. With the scan tool, read all DTCs and record on the repair order.

      Are TCM Power Input DTCs set?

      Yes 

      No 

      • Go To  2
  2. CHECK EVENT DATA 
    NOTE:

    Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.

    1. With the scan tool, read and record the Event Data.

      Does the Event Data show data for DTC P0846?

      Yes 

      • Go To  3

      No 

  3. CHECK FOR MULTIPLE PRESSURE SWITCH DTCS 
    1. With the scan tool, read TCM DTCs.

      Are two or more related pressure switch rationality DTCs set in addition to DTC P0846?

      Yes 

      • Go To  4

      No 

      • Go To  7
  4. CHECK ALL PRESSURE SWITCH STATES IN EVENT DATA 
    1. Refer to the recorded Event Data for DTC P0846.

      Did all of the pressure switches read CLOSED when P0846 set?

      Yes 

      • Perform the diagnostic procedure for DTC P0882 as if the DTC is Active. Refer to DIAGNOSTIC CODE INDEX .

      No 

      • Go To  5
  5. CHECK ALL PRESSURE SWITCH STATES IN EVENT DATA 
    1. Refer to the recorded Event Data for P0846.

      Did all of the pressure switches read OPEN when P0846 set?

      Yes 

      • Go To  6

      No 

      • Go To  7
  6. CHECK FOR LOW LINE PRESSURE 
    1. Refer to the recorded Event Data for P0846.

      Was the Line Pressure less than 40 psi and significantly below the Desired Line Pressure when P0846 set?

      Yes 

      NOTE:

      This transmission is equipped with a solenoid for the Torque Converter Clutch (TCC) that is a Variable Force Solenoid (VFS) with close tolerance Pressure/Inductance (PI) curve. It is necessary to update the TCC solenoid PI data in the PCM when replacing the TCC solenoid, Valve Body or Transmission assembly. This is done with the scan tool using the "Program Torque Converter Solenoid PI Curve" routine. The PI data is located on a 2-D BAR code etched on the body of the TCC solenoid. The data must be entered into the scan tool in order to upload the information to the PCM.

      When replacing the TCC solenoid or Valve Body, obtain the PI data before installing the transmission oil pan. When replacing the transmission, the PI data can be obtained from a 2-D bar code on the exterior of the new transmission. Early build transmissions will have the 2-D barcode label on the right side of the transmission case. Late build transmissions will have the label attached to a machined pad at the top of the case, near the rear of the transmission. If it is suspected that the valve body or TCC VFS has been replaced without uploading the correct PI data into the PCM, the transmission oil pan must be removed to retrieve the information from the 2-D bar code on the body of the TCC solenoid.

      • Repair as necessary to correct low line pressure. Check the fluid level and adjust as necessary. If the fluid level is OK, check the Primary Oil Filter seal for a split, crack or improperly installed. If the filter and seal are OK, check the Main Regulator Valve in the Oil Pump. Refer to the Service Information for the appropriate procedures.
      • If the Valve Body or the TCC VFS solenoid is replaced, remove the external TCC VFS bar code label from the transmission case.
      • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

      No 

  7. CHECK EVENT DATA FOR PARK, REVERSE, OR NEUTRAL 
    NOTE:

    Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.

    1. With the scan tool, read and record the Event Data for P0846.

      Was the Transmission in Park, Reverse, or Neutral when P0846 set?

      Yes 

      • Go To  12

      No 

      • Go To  8
  8. CHECK EVENT DATA FOR 2C PRESSURE SWITCH STATE 
    1. Refer to the recorded Event Data for P0846.

      Was the 2C Pressure Switch CLOSED when P0846 set?

      Yes 

      • Go To  10

      No 

      • Go To  9
  9. COMPARE THE LINE PRESSURE TO THE DESIRED LINE PRESSURE 
    1. Refer to the recorded Event Data for P0846.
    2. Compare the Line Pressure and Desired Line Pressure readings in the recorded Event data.

      Was the Line Pressure less than 40 psi and significantly below the Desired Line Pressure when P0846 set?

      Yes 

      NOTE:

      This transmission is equipped with a solenoid for the Torque Converter Clutch (TCC) that is a Variable Force Solenoid (VFS) with close tolerance Pressure/Inductance (PI) curve. It is necessary to update the TCC solenoid PI data in the PCM when replacing the TCC solenoid, Valve Body or Transmission assembly. This is done with the scan tool using the "Program Torque Converter Solenoid PI Curve" routine. The PI data is located on a 2-D BAR code etched on the body of the TCC solenoid. The data must be entered into the scan tool in order to upload the information to the PCM.

      When replacing the TCC solenoid or Valve Body, obtain the PI data before installing the transmission oil pan. When replacing the transmission, the PI data can be obtained from a 2-D bar code on the exterior of the new transmission. Early build transmissions will have the 2-D barcode label on the right side of the transmission case. Late build transmissions will have the label attached to a machined pad at the top of the case, near the rear of the transmission. If it is suspected that the valve body or TCC VFS has been replaced without uploading the correct PI data into the PCM, the transmission oil pan must be removed to retrieve the information from the 2-D bar code on the body of the TCC solenoid.

      • Repair as necessary to correct low line pressure. Check the fluid level and adjust as necessary. If the fluid level is OK, check the Primary Oil Filter seal for a split, crack or improperly installed. If the filter and seal are OK, check the Main Regulator Valve in the Oil Pump.
      • If the Valve Body or the TCC VFS solenoid is replaced, remove the external TCC VFS bar code label from the transmission case.
      • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

      No 

      • Go To  16
  10. CHECK THE (T147) 2C PRESSURE SIGNAL CIRCUIT 
    1. Turn the ignition off.
    2. Disconnect the PCM C2 harness connector.
      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 the GPEC Diagnostic Adaptor to perform the diagnosis.

    3. Connect the (special tool #10436, Adapter, GPEC Diagnostic) to the appropriate PCM harness connector.
    4. Turn the ignition on.
    5. With the scan tool, read the 2C Pressure Switch state while grounding the (T147) 2C Pressure Signal at the GPEC Diagnostic Adapter with a fused jumper wire.

      Did the 2C Pressure Switch state change from OPEN to CLOSED while grounding the (T147) 2C Pressure Signal?

      Yes 

      • Go To  11

      No 

      • Go To  12
  11. CHECK THE TRANSMISSION SOLENOID/TRS ASSEMBLY 
    1. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
    2. Wiggle the wires while checking for shorted and open circuits.

      Where any problems found?

      Yes 

      No 

  12. ISOLATE AND CHECK THE (T147) 2C PRESSURE SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    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 the GPEC Diagnostic Adaptor to perform the diagnosis.

    1. Important:  The GPEC Diagnostic Adapter can add up to 1.5 Ohms of resistance to the circuit.
    2. Connect the (special tool #10436, Adapter, GPEC Diagnostic) to the appropriate PCM harness connector.
      1. The ignition must be off when checking the continuity of a circuit.
      2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and the component harness connector containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
      3. Before measuring the resistance of any circuit, first measure the resistance between the two leads of the DVOM. Note:  The meter leads can add resistance to the measurement value.
      4. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
      5. Connect the other lead to the circuit being tested at the GPEC Diagnostic Adapter and measure the resistance of the circuit.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  13

      No 

  13. ISOLATE AND CHECK THE (T147) 2C PRESSURE SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    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 the GPEC Diagnostic Adaptor to perform the diagnosis.

    1. The ignition must be off when checking a circuit for continuity to ground.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Connect the negative lead of the DVOM to a known good ground.
    4. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for continuity between the circuit and ground.
    NOTE:

    There should be no continuity between ground and the circuit being tested.

    Is there continuity between ground and the circuit being tested?

    Yes 

    • Repair the circuit for a short to ground. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
    • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

    No 

    • Go To  14
  14. ISOLATE AND CHECK THE (T147) 2C PRESSURE SIGNAL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE PCM HARNESS CONNECTOR 
    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 the GPEC Diagnostic Adaptor to perform the diagnosis.

    1. The ignition must be off when performing a resistance check to find a short between circuits.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested. At this time leave all in-line connectors connected. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Connect one lead of the DVOM to the circuit being tested at the GPEC Diagnostic Adapter.
    4. With the other lead of the DVOM probe all other circuits at the GPEC Diagnostic Adapter.
    NOTE:

    With the circuit isolated there should be no continuity between the circuit being tested and any other circuit.

    Is there continuity between the circuit being tested and any other circuit?

    Yes 

    • Repair the short between the circuits that have continuity. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
    • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

    No 

    • Go To  15
  15. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all PCM harness connectors.
    2. Disconnect the (special tool #10436, Adapter, GPEC Diagnostic) and remove from vehicle.
    3. Disconnect all related in-line harness connections (if equipped).
    4. Disconnect the related component harness connectors.
    5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Perform a terminal drag test on each connector terminal to verify proper terminal tension.

      Repair any conditions that are found.

    6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    9. With the scan tool, erase DTCs.
    10. Using the recorded Event and Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    11. With the scan tool, read PCM DTCs.

      Did the DTC return?

      Yes 

      NOTE:

      This transmission is equipped with a solenoid for the Torque Converter Clutch (TCC) that is a Variable Force Solenoid (VFS) with close tolerance Pressure/Inductance (PI) curve. If replacing the PCM, it is necessary to transfer the PI data from the old PCM to the new PCM using the scan tool. If the PCM being replaced is non-responsive, the PI data can be retrieved from a 2-D bar code on the exterior of the transmission case. This is done with the scan tool using the "Program Torque Converter Solenoid PI Curve" routine.

      Early build transmissions will have the 2-D barcode label on the right side of the transmission case. Late build transmissions will have the label attached to a machined pad at the top of the case, near the rear of the transmission. The data must be entered into the scan tool in order to upload the information to the PCM. In the event that the exterior BAR code is missing, or it is suspected that the valve body or TCC solenoid has been replaced without uploading the correct PI data into an existing PCM, the transmission oil pan must be removed to retrieve the information from the 2-D bar code on the body of the TCC solenoid.

      No 

  16. CHECK IF THE NO. 5 CHECK BALL IS CUT OR DAMAGED 
    1. Turn the ignition off.
    2. Remove the Valve Body Assembly in accordance with the Service Information.
    3. Inspect the No. 5 check ball for any cuts or damage.
    4. Inspect the 2C accumulator piston and seals and also the 2C tower seal on top of the valve body.

      Where any problems found?

      Yes 

      NOTE:

      This transmission is equipped with a solenoid for the Torque Converter Clutch (TCC) that is a Variable Force Solenoid (VFS) with close tolerance Pressure/Inductance (PI) curve. It is necessary to update the TCC solenoid PI data in the PCM when replacing the TCC solenoid, Valve Body or Transmission assembly. This is done with the scan tool using the "Program Torque Converter Solenoid PI Curve" routine. The PI data is located on a 2-D BAR code etched on the body of the TCC solenoid. The data must be entered into the scan tool in order to upload the information to the PCM.

      When replacing the TCC solenoid or Valve Body, obtain the PI data before installing the transmission oil pan. When replacing the transmission, the PI data can be obtained from a 2-D bar code on the exterior of the new transmission. Early build transmissions will have the 2-D barcode label on the right side of the transmission case. Late build transmissions will have the label attached to a machined pad at the top of the case, near the rear of the transmission. If it is suspected that the valve body or TCC VFS has been replaced without uploading the correct PI data into the PCM, the transmission oil pan must be removed to retrieve the information from the 2-D bar code on the body of the TCC solenoid.

      • Repair as necessary. Check for excessive clutch debris in the transmission oil pan. If excessive clutch debris is present, repair 2C clutch as necessary.
      • If the Valve Body or the TCC VFS solenoid is replaced, remove the external TCC VFS bar code label from the transmission case.
      • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

      No 

      • Go To  17
  17. CHECK FOR EXCESSIVE FLUID LEAKAGE WITHIN 2C CLUTCH CIRCUIT 
    1. Air check the 2C Clutch hydraulic circuit. Refer to the Service Information.
      NOTE:

      This hydraulic clutch circuit contains a small bleed orifice. Small leakage is considered normal.

      Was there excessive air leakage in the 2C Clutch hydraulic circuit?

      Yes 

      NOTE:

      This transmission is equipped with a solenoid for the Torque Converter Clutch (TCC) that is a Variable Force Solenoid (VFS) with close tolerance Pressure/Inductance (PI) curve. It is necessary to update the TCC solenoid PI data in the PCM when replacing the TCC solenoid, Valve Body or Transmission assembly. This is done with the scan tool using the "Program Torque Converter Solenoid PI Curve" routine. The PI data is located on a 2-D BAR code etched on the body of the TCC solenoid. The data must be entered into the scan tool in order to upload the information to the PCM.

      When replacing the TCC solenoid or Valve Body, obtain the PI data before installing the transmission oil pan. When replacing the transmission, the PI data can be obtained from a 2-D bar code on the exterior of the new transmission. Early build transmissions will have the 2-D barcode label on the right side of the transmission case. Late build transmissions will have the label attached to a machined pad at the top of the case, near the rear of the transmission. If it is suspected that the valve body or TCC VFS has been replaced without uploading the correct PI data into the PCM, the transmission oil pan must be removed to retrieve the information from the 2-D bar code on the body of the TCC solenoid.

      • Repair as necessary.
      • If the Valve Body or the TCC VFS solenoid is replaced, remove the external TCC VFS bar code label from the transmission case.
      • Perform the TRANSMISSION VERIFICATION TEST. Refer to TRANSMISSION VERIFICATION TEST .

      No 

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