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 DTCSIgnition on, engine not running.
With the scan tool, check for other transmission DTCs.
Are there any Loss of Prime and/or TCM Power Input DTCs present also?
Yes
- Refer to the Transmission category and perform the appropriate symptom. If the DTC P0944 is present, perform its respective test first. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - DIAGNOSIS AND TESTING)
No
- Go To 2
2. CHECK IF DTC P0841 IS PRESENT
With the scan tool, check the DTC EVENT DATA for P0841.
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
- Go To 10
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
- Go To 14
5. CHECK THE TCM AND WIRING
Turn the ignition off to the lock position.
Remove the Starter Relay.
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.
Install the Transmission Simulator, Miller tool #8333.
Ignition on, engine not running.
Turn the Pressure Switch selector to LR on the Transmission Simulator.
With the scan tool, monitor the LR Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.
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
- Go To 10
6. CHECK WIRING AND CONNECTORS
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.
Were there any problems found?
Yes
- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 7
7. CHECK IF DTC SET IN FIRST GEAR
With the DTC EVENT DATA recorded earlier, check what gear the transmission was in when the DTC P0841 was set.
Does the DTC EVENT DATA show the Present Gear as first gear when the DTC P0841 was set ?
Yes
- Go To 8
No
- Replace the Transmission Solenoid/TRS Assembly per the Service Information.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
8. CHECK IF THE NO. 1 CHECK BALL IS CUT OR DAMAGED
Turn the ignition off to the lock position.
Remove the Transmission Valve Body per the Service Information.
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 LR Clutch assembly. Refer to the Service Information for proper repair procedures.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 9
9. CHECK IF THE REVERSE CARRIER SNAP RING IS DISLODGED
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 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No
- Replace the Transmission Solenoid/TRS Assembly per the Service Information.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
10. CHECK THE (T50) LR PRESSURE SWITCH SENSE CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool #8333 if connected in a previous step or disconnect the Transmission Solenoid/TRS Assembly harness connector.
Disconnect the TCM harness connector.
Measure the resistance of the (T50) LR Pressure Switch Sense circuit from the Solenoid/TRS Assembly harness connector and the TCM harness connector.
Is the resistance above 5.0 ohms?
Yes
- Repair the (T50) LR Pressure Switch Sense circuit for an open.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 11
11. CHECK THE (T50) LR PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND
Measure the resistance between ground and the (T50) LR Pressure Switch Sense circuit.
Is the resistance below 5.0 ohms?
Yes
- Repair the (T50) LR Pressure Switch Sense circuit for a short to ground.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 12
12. CHECK THE TCM POWERS AND GROUNDS
Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 13
13. CHECK IF THE DTC RESETS
With the scan tool, clear the DTC and road test the vehicle.
Try to duplicate the conditions in which the DTC originally set using the DTC EVENT DATA recorded earlier.
Did the DTC P0841 reset?
Yes
- Replace the TCM per the Service Information. With the scan tool, perform QUICK LEARN.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 17
14. CHECK FOR LOW LINE PRESSURE
In the DTC 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 per the Service Information.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 15
15. CHECK THE (T50) LR PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid/TRS Assembly harness connector.
Disconnect the TCM harness connector.
Measure the resistance between the (T50) LR Pressure Switch Sense circuit and all other circuits in the Transmission Solenoid/TRS Assembly harness connector.
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
- Repair the (T50) LR Pressure Switch Sense circuit for a short to other circuit(s).
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 16
16. CHECK IF DTC RESETS
With the scan tool, clear the DTC and road test the vehicle.
Try to duplicate the conditions in which the DTC originally set using the DTC EVENT DATA recorded earlier.
Did the DTC P0841 reset?
Yes
- Replace the Transmission Solenoid/TRS Assembly per the Service Information.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Go To 17
17. CHECK 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 DTC EVENT DATA to help identify the conditions in which the DTC was set.
Were there any problems found?
Yes
- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)
No
- Test Complete.