P0841-LR PRESSURE SWITCH RATIONALITY





For a complete wiring diagram Refer to Section 8W

Theory of Operation


The Transmission system uses five pressure switches to monitor the fluid pressure in the LR, 2C, 4C, UD, and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown.


  • When Monitored:

    Continuously with the ignition on and engine running.

  • Set Condition:

    The DTC will set if the LR Pressure Switch reads open or closed at the wrong time in a given gear.


Possible Causes
  
LOSS OF PRIME AND/OR TCM POWER INPUT DTCS PRESENT
  
LOW FLUID LEVEL
  
LOW LINE PRESSURE
  
REVERSE CARRIER SNAP RING DISLODGED
  
CRACKED OR MIS-INSTALLED PRIMARY OIL FILTER OR FILTER SEAL
  
STICKING MAIN REGULATOR VALVE IN PUMP VALVE BODY
  
NO. 1 CHECK BALL CUT OR DAMAGED
  
WIRING AND CONNECTORS
  
(T50) LR PRESSURE SWITCH SENSE CIRCUIT OPEN
  
(T50) LR PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
  
(T50) LR PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
  
TRANSMISSION SOLENOID/TRS ASSEMBLY
  
TRANSMISSION CONTROL MODULE
  

Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)


GEAR
  		L/R
  		2C
  		4C
  		UD
  		OD
  
REVERSE
  		OPEN
  		OPEN
  		OPEN
  		OPEN
  		OPEN
  
P/N
  		CLOSED**
  		OPEN
  		OPEN
  		OPEN
  		OPEN
  
1ST
  		CLOSED*
  		OPEN
  		OPEN
  		CLOSED
  		OPEN
  
2ND
  		OPEN
  		CLOSED
  		OPEN
  		CLOSED
  		OPEN
  
2ND PRIME
  		OPEN
  		OPEN
  		CLOSED
  		CLOSED
  		OPEN
  
3RD
  		OPEN
  		OPEN
  		OPEN
  		CLOSED
  		CLOSED
  
4TH
  		OPEN
  		OPEN
  		CLOSED
  		OPEN
  		CLOSED
  
5TH
  		OPEN
  		CLOSED
  		OPEN
  		OPEN
  		CLOSED
  
*L/R is closed if output speed is below 100 rpm in Drive and Manual 2. L/R is closed in Manual 1.
  
**May be open when rolling in Neutral or at low oil temperatures.
  



Diagnostic Test

1.CHECK FOR OTHER DTCS




Are there any Loss of Prime and/or TCM Power Input DTCs present also?

Yes


No
  • Go To 2

2.CHECK IF DTC P0841 IS PRESENT


NOTE: Make sure to record all DTC EVENT DATA stored in the scan tool for future reference in this test procedure.



Does the DTC EVENT DATA show the DTC P0841?

Yes
  • Go To 3


No
  • Refer to the Symptom Category and perform diagnostics for the DTC reported in the DTC EVENT DATA.

3.CHECK IF DTC SET IN REVERSE


Does the DTC EVENT DATA show the DTC P0841 set while in Reverse?

Yes


No
  • Go To 4

4.CHECK IF THE LR PRESSURE SWITCH WAS CLOSED


Does the DTC EVENT DATA show the LR Pressure Switch reading CLOSED when the DTC P0841 was set?

Yes
  • Go To 5


No

5.CHECK THE TCM AND WIRING



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


WARNING: The Starter Relay must be removed from the PDC. Failure to do so can result in personal injury or death.


NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.







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

Yes
  • Go To 6


No

6.CHECK WIRING AND CONNECTORS




Were there any problems found?

Yes


No
  • Go To 7

7.CHECK IF DTC SET IN FIRST GEAR



Does the DTC EVENT DATA show the Present Gear as first gear when the DTC P0841 was set ?

Yes
  • Go To 8


No

8.CHECK IF THE NO. 1 CHECK BALL IS CUT OR DAMAGED





Is the No. 1 Check Ball cut or damaged?

Yes


No
  • Go To 9

9.CHECK IF THE REVERSE CARRIER SNAP RING IS 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 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.


No

10.CHECK THE (T50) LR PRESSURE SWITCH SENSE CIRCUIT FOR AN OPEN








Is the resistance above 5.0 ohms?

Yes


No

11.CHECK THE (T50) LR PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND





Is the resistance below 5.0 ohms?

Yes


No

12.CHECK THE TCM POWERS AND GROUNDS



Were there any problems found?

Yes


No

13.CHECK IF THE DTC RESETS




Did the DTC P0841 reset?

Yes


No

14.CHECK FOR LOW 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 per the Service Information.
  • Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)


No

15.CHECK THE (T50) LR PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT








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

Yes


No

16.CHECK IF DTC RESETS




Did the DTC P0841 reset?

Yes


No

17.CHECK WIRING AND CONNECTORS






Were there any problems found?

Yes


No
  • Test Complete.