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 L/R, 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 L/R Pressure Switch reads open or closed at the wrong time in a given gear.

Possible Causes

LOSS OF PRIME AND/OR TIPM DTC 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) L/R PRESSURE SWITCH SENSE CIRCUIT OPEN

(T50) L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND

(T50) L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE

TRANSMISSION SOLENOID/TRS ASSEMBLY

POWERTRAIN 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
3TH	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 IF OTHER RELATED DTCS PRESENT

Ignition on, engine not running.
With the scan tool, check for other transmission DTCs.

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

Yes

Refer to the Transmission category and perform the appropriate symptom. If the DTC P0944 is present, perform its respective test first.

Go To 2

2. CHECK IF THE CONDITION 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

Refer to the Transmission category and perform diagnostics for the DTC reported in the DTC EVENT DATA.

3. CHECK IF THE DTC SET IN REVERSE

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

Yes

Go To 10

Go To 4

4. CHECK IF THE L/R PRESSURE SWITCH IS CLOSED

Does the DTC EVENT DATA show the L/R Pressure Switch reading CLOSED when the DTC P0841 was set?

Yes

Go To 5

Go To 14

5. CHECK THE PCM AND WIRING

Turn the ignition off to the lock position.
Remove the Ignition Switch Feed fuse from the TIPM.

CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.

WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in personal injury or death.

Install the Transmission Simulator, Miller tool #8333.
Ignition on, engine not running.
Turn the Pressure Switch selector to L/R on the Transmission Simulator.
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

Go To 10

6. CHECK FOR 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. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Go To 7

7. CHECK IF THE 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

Replace the Transmission Solenoid/TRS Assembly per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE/TRANS SOLENOID/TRS ASSY - REMOVAL)
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (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 L/R Clutch assembly. Refer to the Service Information for proper repair procedures.

Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Go To 9

9. CHECK IF THE REVERSE CARRIER SNAP RING IS DISLODGED AND THE 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. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

Replace the Transmission Solenoid/TRS Assembly per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE/TRANS SOLENOID/TRS ASSY - REMOVAL)
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

10. CHECK THE (T50) L/R 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 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) L/R Pressure Switch Sense circuit between the Solenoid/TRS Assembly harness connector and the appropriate terminal of the Miller tool #8815.

Is the resistance above 5.0 ohms?

Yes

Repair the (T50) L/R Pressure Switch Sense circuit for an open.