Diagnostic Test

1. Ignition ON, Engine Not Running.
2. With the scan tool, check for transmission DTCs.

   Are any Transmission Loss of Prime, TCM Power Input and/or TCM Power Control Circuit DTCs present?

   Yes 

   • Refer to DIAGNOSIS AND TESTING  and perform the appropriate diagnostic procedure. If the DTC P0944 is present, perform its respective test first.

   No 

   • Go To  2

1. With the scan tool, check the Event Data for P0841.
   NOTE:

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

   Does the Event Data show DTC P0841?

   Yes 

   • Go To  3

   No 

   • Refer to DIAGNOSIS AND TESTING  and perform diagnostics for the DTC reported in the Event Data.

Does the Event Data show DTC P0841 set while in Reverse?

Yes 

• Go To  10

No 

• Go To  4

Does the Event Data show the L/R Pressure Switch reading CLOSED when DTC P0841 set?

Yes 

• Go To  5

No 

• Go To  14

1. Turn the ignition OFF.
2. Remove the Starter Relay from the PDC.
   CAUTION:

   Removal of the Starter Relay will prevent the vehicle from being started in gear.

   WARNING:

   The Starter Relay must be removed. Failure to do so can result in possible serious or fatal injury.

3. Install Transmission Simulator (special tool #8333B, Simulator, Transmission).
4. Ignition ON, Engine Not Running.
5. Turn the Pressure Switch selector to L/R on the Transmission Simulator.
6. With the scan tool, monitor the L/R Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.

   Did the L/R Pressure Switch state change from open to closed while pressing the Pressure Switch Test button on the Transmission Simulator?

   Yes 

   • Go To  6

   No 

   • Go To  10

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.

   Were any problems found?

   Yes 

   • Repair as necessary.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  7

In the Event Data recorded earlier, does the Event Data show the Present Gear as first gear when DTC P0841 set ?

Yes 

• Go To  8

No 

• Replace the Transmission Solenoid/TRS Assembly in accordance with the Service Information.
• Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

1. Turn the ignition OFF.
2. Remove the Transmission Valve Body in accordance with the Service Information.
3. Check the No. 1 Check Ball for any possible cuts or damage.

   Is the No. 1 Check Ball cut or damaged?

   Yes 

   • Replace the No. 1 Check Ball and check for clutch debris in the transmission oil pan. If there is excessive debris, perform internal repairs to the L/R Clutch assembly.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  9

1. Looking through the windows in the bottom of the case, check whether the snap ring at the front of the Reverse (center) Carrier has dislodged.
   NOTE:

   It may be necessary to pry the Input Annulus Gear Shell rearward to check this snap ring.

   Is the Reverse Carrier Snap Ring dislodged?

   Yes 

   • Repair as necessary.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Replace the Transmission Solenoid/TRS Assembly in accordance with the Service Information.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

1. Turn the ignition OFF.
2. Disconnect the Transmission Simulator (special tool #8333B, Simulator, Transmission) if connected in a previous step or disconnect the Transmission Solenoid/TRS Assembly harness connector.
3. Disconnect the PCM C1 harness connector.
4. Measure the resistance of the (T50) L/R Pressure Control circuit between the Transmission Solenoid/TRS Assembly harness connector and the appropriate terminal of the PCM C1 harness connector.

   Is the resistance above 5.0 ohms?

   Yes 

   • Repair the (T50) L/R Pressure Control circuit for an open.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  11

1. Measure the resistance between ground and the (T50) L/R Pressure Control circuit.

   Is the resistance below 5.0 ohms?

   Yes 

   • Repair the (T50) L/R Pressure Control circuit for a short to ground.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  12

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.

   Were any problems found?

   Yes 

   • Repair as necessary.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  13

1. With the scan tool, clear the DTC and road test the vehicle.
2. Try to duplicate the conditions in which the DTC set using the Event Data recorded earlier.

   Did DTC P0841 reset?

   Yes 

   • Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. With the scan tool, perform a Quick Learn. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL and MODULE, POWERTRAIN CONTROL, 6.7L DIESEL [ETK], REMOVAL .
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  17

1. In the Event Data recorded earlier, compare the Line Pressure and the Desired Line Pressure.

   Is the Line Pressure less than 40 psi, and significantly below the Desired Line Pressure?

   Yes 

   • Repair as necessary to correct low line pressure. Check for low fluid level. Check the Primary Oil Filter seal for a split, crack or improperly installed. Refer to the Service Information for the proper installation procedure. If the fluid level and Primary Oil Filter are OK, check the Main Regulator Valve in the Oil Pump in accordance with the Service Information.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  15

1. Turn the ignition OFF.
2. Disconnect the Transmission Solenoid/TRS Assembly harness connector.
3. Disconnect all PCM harness connectors.
4. Measure the resistance between the (T50) L/R Pressure Control circuit and all other circuits in the Transmission Solenoid/TRS Assembly harness connector.

   Is the resistance below 5.0 ohms between the (T50) L/R Pressure Control circuit and all other circuit(s) in the Transmission Solenoid/TRS Assembly harness connector?

   Yes 

   • Repair the (T50) L/R Pressure Control circuit for a short to other circuit(s).
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  16

1. With the scan tool, clear the DTC and road test the vehicle.
2. Try to duplicate the conditions in which the DTC set using the Event Data recorded earlier.

   Did DTC P0841 reset?

   Yes 

   • Replace the Transmission Solenoid/TRS Assembly in accordance with the Service Information.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Go To  17

1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.
4. With the scan tool, check the Event Data to help identify the conditions in which the DTC set.

   Were any problems found?

   Yes 

   • Repair as necessary.
   • Perform the TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

   No 

   • Test Complete.