45RFE / 545RFE Transmission
P0841-LR PRESSURE SWITCH RATIONALITY
For the Transmission circuit diagram, refer to Wiring Diagram Information.
^ 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 TRANSMISSION CONTROL RELAY DTC PRESENT
- LOW FLUID LEVEL
- LOW LINE PRESSURE
- REVERSE CARRIER SNAP RING DISLODGED
- CRACKED OR MISINSTALLED 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
- POWERTRAIN CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Verification Tests
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.
Diagnostic Test
1. OTHER RELATED DTC'S PRESENT
Ignition on, engine not running. With the scan tool, check for other transmission DTC's.
Are there any Loss of Prime and/or Transmission Control Relay related DTC's present?
Yes >>Refer to the Transmission category and perform the appropriate symptom. If the DTC P0944 is present, perform its respective test first.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No >>Go To 2
2. CONDITION P0841 PRESENT
With the scan tool, check the EATX DTC EVENT DATA for P0841.
NOTE: Make sure to record all EATX DTC EVENT DATA stored in the scan tool for future reference in this test procedure.
Does the EATX 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 EATX DTC EVENT DATA.
3. DTC SET IN REVERSE
Does the EATX DTC EVENT DATA show the DTC P0841 set while in Reverse?
Yes >>Go To 10
No >>Go To 4
4. LR PRESSURE SWITCH CLOSED
Does the EATX 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. 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.
NOTE: Check connectors - Clean/repair as necessary.
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. POOR WIRING AND CONNECTIONS
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. Verification Tests
No >>Go To 7
7. DTC SET IN FIRST GEAR
With the EATX DTC EVENT DATA recorded earlier, check what gear the transmission was in when the DTC P0841 was set.
Does the EATX 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. Verification Tests
8. NO. 1 CHECK BALL 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. Verification Tests
No >>Go To 9
9. REVERSE CARRIER SNAP RING DISLODGED OR TRANSMISSION SOLENOID/TRS ASSEMBLY
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. Verification Tests
No >>Replace the Transmission Solenoid/TRS Assembly per the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
10. (T50) LR PRESSURE SWITCH SENSE CIRCUIT 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 PCM C4 harness connector and connect Miller tool #8815.
NOTE: Check connectors - Clean/repair as necessary.
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 (T50) LR Pressure Switch Sense circuit from the Solenoid/TRS Assembly harness connector to the appropriate terminal of the Miller tool #8815.
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. Verification Tests
No >>Go To 11
11. (T50) LR PRESSURE SWITCH SENSE CIRCUIT 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. Verification Tests
No >>Go To 12
12. PCM POWERS AND GROUNDS
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 there any problems found?
Yes >>Repair as necessary.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No >>Go To 13
13. ROAD TEST THE VEHICLE
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 EATX DTC EVENT DATA recorded earlier.
Did the DTC P0841 reset?
Yes >>Replace the PCM per the Service Information. With the scan tool, perform QUICK LEARN.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No >>Go To 17
14. LOW LINE PRESSURE
In the EATX 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. Verification Tests
No >>Go To 15
15. (T50) LR PRESSURE SWITCH SENSE CIRCUIT SHORT TO OTHER CIRCUITS
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 (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. Verification Tests
No >>Go To 16
16. ROAD TEST THE VEHICLE
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 EATX 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. Verification Tests
No >>Go To 17
17. 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.
Were there any problems found?
Yes >>Repair as necessary.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No >>Test Complete.