P0846
P0846-2C PRESSURE SWITCH RATIONALITY
For a complete wiring diagram Refer to Diagrams/Electrical Electrical Diagrams
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, engine running, with the transmission in gear.
- Set Condition:
The DTC is set if the 2C Pressure Switch reads open or closed at the wrong time in a given gear.
Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting procedure before proceeding. 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure
Diagnostic Test
1. DETERMINE IF RELATED TCM POWER INPUT DTCS ARE PRESENT
With the scan tool, check for other transmission DTCs.
Are there any TCM Power Input DTCs present also?
Yes
- Refer to the Transmission and Drivetrain and perform the appropriate symptom.
No
- Go To 2
2. CHECK IF THE DTC IS CURRENT
With the scan tool, check the DTC EVENT DATA.
Does the DTC EVENT DATA show data for DTC P0846?
Yes
- Go To 3
No
- Refer to the Transmission and Drivetrain and perform the appropriate symptom shown in the DTC EVENT DATA.
3. CHECK FOR MULTIPLE DTCS
With the scan tool, check for other transmission DTCs.
Are there two or more related pressure switch rationality DTCs present in addition to P0846?
Yes
- Go To 4
No
- Go To 7
4. CHECK IF ALL PRESSURE SWITCHES READ CLOSED
With the scan tool, check the DTC EVENT DATA for P0846.
NOTE: Make sure to record all DTC EVENT DATA stored in the scan tool for future reference in this test procedure.
Do all the pressure switches read CLOSED in the DTC EVENT DATA for P0846?
Yes
- Refer to Transmission and drivetrain and perform diagnostics for P0882.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Go To 5
5. CHECK IF ALL PRESSURE SWITCHES READ OPEN
In the DTC EVENT DATA recorded earlier, read the state of all pressure switches.
Do all the pressure switches read OPEN?
Yes
- Go To 6
No
- Go To 7
6. 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 fluid level and adjust as necessary. If fluid level is OK, check the Primary Oil Filter seal for a split, crack, or improperly installed. If the filter and seal are OK, check the Main Regulator Valve in the Oil Pump.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Replace the Transmission Solenoid/TRS Assembly.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
7. CHECK IF THE DTC SET IN PARK REVERSE OR NEUTRAL
With the scan tool, check the DTC EVENT DATA for P0846.
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 P0846 set in Park, Reverse, or Neutral?
Yes
- Go To 12
No
- Go To 8
8. CHECK IF THE 2C PRESSURE SWITCH READS CLOSED
With the scan tool, check the DTC EVENT DATA for P0846.
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 2C Pressure Switch reading CLOSED?
Yes
- Go To 10
No
- Go To 9
9. COMPARE THE LINE PRESSURE TO THE DESIRED 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 fluid level and adjust as necessary. If fluid level is OK, check the Primary Oil Filter seal for a split, crack, or improperly installed. If the filter and seal are OK, check the Main Regulator Valve in the Oil Pump.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Go To 15
10. CHECK THE PCM 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.
With the Transmission Simulator, turn the Pressure Switch selector switch to the 2C position.
With the scan tool, monitor the 2C Pressure Switch while pressing the Pressure Switch test button on the Transmission Simulator.
Did the state of the 2C Pressure Switch change while pressing the Pressure Switch Test button?
Yes
- Go To 11
No
- Go To 12
11. CHECK THE TRANSMISSION SOLENOID/TRS ASSEMBLY
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.
Where there any problems found?
Yes
- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Replace the Transmission Solenoid/TRS Assembly.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
12. CHECK THE (T147) 2C PRESSURE SWITCH SENSE CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool #8333.
Disconnect the PCM C4 harness connector.
Connect Miller tool #8815 to the PCM C4 harness connector.
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 (T147) 2C Pressure Switch Sense circuit from the appropriate terminal of Miller tool #8815 to the Transmission Solenoid/TRS Assembly harness connector.
Is the resistance above 5.0 ohms?
Yes
- Repair the (T147) 2C Pressure Switch Sense circuit for an open.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Go To 13
13. CHECK THE (T147) 2C PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND
Measure the resistance between ground and the (T147) 2C Pressure Switch Sense circuit.
Is the resistance below 5.0 ohms?
Yes
- Repair the (T147) 2C Pressure Switch Sense circuit for a short to ground.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Go To 14
14. CHECK THE (T147) 2C PRESSURE SWITCH SENSE CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Measure the resistance between the (T147) 2C Pressure Switch Sense circuit and all the other circuits in the Transmission Solenoid/TRS Assembly harness connector.
Is the resistance below 5.0 ohms?
Yes
- Repair the (T147) 2C Pressure Switch Sense circuit for a short to another circuit(s).
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Replace the Powertrain Control Module. With the scan tool, perform the QUICK LEARN procedure.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
15. CHECK IF THE #5 AND/OR #7 CHECK BALL IS CUT OR DAMAGED
Turn the Ignition off to the lock position.
Remove the Valve Body Assembly.
Inspect the #5 and #7 check balls for any cuts or damage.
Check for an extra check ball in the passage downstream from the #7 check ball pocket.
Inspect the 2C accumulator piston and seals and also the 2C tower seal on top of the valve body.
Where there any problems found?
Yes
- Repair as necessary. Check for excessive clutch debris in the transmission oil pan. If excessive clutch debris is present, repair 2C clutch as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Go To 16
16. CHECK FOR EXCESSIVE FLUID LEAKAGE WITHIN 2C CLUTCH CIRCUIT
Air check the 2C Clutch hydraulic circuit.
NOTE: This hydraulic clutch circuit contains a small bleed orifice. Small leakage is considered normal.
Was there excessive air leakage in the 2C Clutch hydraulic circuit?
Yes
- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test
No
- Replace the Transmission Solenoid/TRS Assembly.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 45RFE/545RFE Transmission Verification Test