P0846
P0846-2C PRESSURE SWITCH RATIONALITY
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.
Possible Causes
- RELATED RELAY DTC'S PRESENT
- (T147) 2C PRESSURE SWITCH SENSE CIRCUIT OPEN
- (T147) 2C PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
- (T147) 2C PRESSURE SWITCH SENSE CIRCUIT SHORT TO OTHER CIRCUITS
- EXCESSIVE FLUID LEAKAGE IN 2C CLUTCH CIRCUIT
- NO. 5 AND/OR NO. 7 CHECK BALL CUT OR DAMAGED
- EXTRA CHECK BALL DOWNSTEAM THE NO. 7 CHECK BALL SOCKET
- LOW LINE PRESSURE
- TRANSMISSION SOLENOID/TRS ASSEMBLY
- POWERTRAIN CONTROL MODULE
- WIRING AND CONNECTORS
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Testing and Inspection
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 near as shown.
Diagnostic Test
1. DETERMINING IF RELATED RELAY DTC'S ARE PRESENT
With the scan tool, check for other transmission DTC's.
Are there any Transmission Control Relay related DTC's present?
Yes >>Refer to the Transmission category and perform the appropriate symptom.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
No >>Go To 2
2. EATX DTC DATA SHOW CURRENT DTC
With the scan tool, check the EATX DTC EVENT DATA.
Does the EATX DTC EVENT DATA show data for DTC P0846?
Yes >>Go To 3
No >>Refer to the Transmission category and perform the appropriate symptom shown in the EATX DTC EVENT DATA.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
3. MULTIPLE DTCS PRESENT
With the scan tool, check for other transmission DTC's.
Are there two or more related pressure switch rationality DTCs present in addition to P0846?
Yes >>Go To 4
No >>Go To 7
4. RELATED DTC PRESENT
With the scan tool, check the EATX DTC EVENT DATA for P0846.
Note: Make sure to record all EATX DTC EVENT DATA stored in the scan tool for future reference in this test procedure.
Do all the pressure switches read CLOSED in the EATX DTC EVENT DATA for P0846?
Yes >>Refer to Transmission category and perform diagnostics for P0888.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
No >>Go To 5
5. EATX DTC EVENT DATA READ OPEN
In the EATX 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. 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 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 - VER 1.
No >>Replace the Transmission Solenoid/TRS Assembly per the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
7. EATX DTC EVENT DATA READ PARK REVERSE OR NEUTRAL
With the scan tool, check the EATX DTC EVENT DATA for P0846.
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 P0846 set in Park, Neutral, or Reverse?
Yes >>Go To 12
No >>Go To 8
8. EATX DTC EVENT DATA READ CLOSED
With the scan tool, check the EATX DTC EVENT DATA for P0846.
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 2C Pressure Switch reading CLOSED?
Yes >>Go To 10
No >>Go To 9
9. PRIMARY OIL FILTER SEAL
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 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 - VER 1.
No >>Go To 14
10. 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.
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. 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 - VER 1.
No >>Replace the Transmission Solenoid/TRS Assembly per the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
12. (T147) 2C PRESSURE SWITCH SENSE CIRCUIT OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Simulator, Miller tool # 8333.
Disconnect the PCM C4 harness connector.
Note: Check connectors - Clean/repair as necessary. 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 - VER 1.
No >>Go To 13
13. (T147) 2C PRESSURE SWITCH SENSE CIRCUIT 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 - VER 1.
No >>Replace the Powertrain Control Module per the Service Information. With the scan tool, perform the QUICK LEARN procedure.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.
14. # 5 AND/OR # 7 CHECK BALL CUT OR DAMAGED
Turn the Ignition off to the lock position.
Remove the Valve Body Assembly per the Service Information.
Inspect the # 5 and # 7 check balls for any cuts or damage.
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 - VER 1.
No >>Go To 15
15. EXCESSIVE FLUID LEAKAGE WITH 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 - VER 1.
No >>Replace the Transmission Solenoid/TRS Assembly per the Service Information.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1.