P0871
P0871-OD PRESSURE SWITCH RATIONALITY
- When Monitored:
Continuously with the ignition on and engine running.
- Set Condition:
The appropriate DTC is set if one of the pressure switches are open or closed at the wrong time in a given gear.
Possible Causes
- RELATED RELAY DTC'S PRESENT
- LINE PRESSURE DTCS PRESENT
- NO. 4 OR 6 CHECK BALL CUT OR DAMAGED
- (T9) OD PRESSURE SWITCH SENSE CIRCUIT OPEN
- (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
- (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO ANOTHER CIRCUIT
- LOW LINE PRESSURE
- WIRING AND CONNECTORS
- CUT OD/REV PISTON SEAL
- BROKEN OR MISSING DO/REV PISTON BLEED ORIFICE
- BROKEN REACTION SHAFT SUPPORT SEAL RING
- POOR MACHINING ON PUMP VALVE BODY FACE
- BROKEN OR MISSING DRIBBLER ORIFICE ASSEMBLY IN REACTION SHAFT SUPPORT
- TRANSMISSION SOLENOID/TRS ASSEMBLY
- CUT OD ACCUMULATOR PISTON SEAL
- CRACKED OD ACCUMULATOR PISTON
- BROKEN OR MISSING OD BLEED ORIFICE IN MAIN VALVE BODY
- POWERTRAIN CONTROL MODULE
Always perform the 45RFE/545RFE 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 gear 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. LINE PRESSURE DTCS PRESENT
With the scan tool, read Transmission DTCs.
Are there any Line Pressure DTCs 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 3
3. CHECK FOR OTHER PRESSURE SWITCH DTCS
With the scan tool, check Transmission DTCs.
Are there two or more other pressure switch rationality DTCs present in addition to P0871?
YES >>Go To 5
NO >>Go To 4
4. CHECK IF DTC IS CURRENT
With the scan tool, check and record the DTC EVENT DATA.
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 data for P0871
YES >>Go To 8
NO >>Refer to the Transmission Category and perform the appropriate symptom.
5. RELATED DTC PRESENT
With the scan tool, check and record the DTC EVENT DATA.
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?
YES >>Refer to the Transmission category and perform diagnostics for P0888. P Code Charts Follow instructions as if the DTC is current.
NO >>Go To 6
6. CHECK IF 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 7
NO >>Go To 8
7. CHECK FOR LOW LINE PRESSURE
In the DTC EVENT DATA recorded earlier, compare the Line Pressure to 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 weal for a spit, crack, or improperly installed. If the filer and seal are OK, check the Main Regulator Valve in the Oil Pump.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Replace the Transmission Solenoid/TRS Assembly.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
8. CHECK IF IN PARK, NEUTRAL, OR REVERSE
Ignition on, engine not running.
With the scan tool, read and record the DTC EVENT DATA for P0871.
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 OD Pressure Switch DTC set while in Park, Neutral, or Reverse?
YES >>Go To 18
NO >>Go To 9
9. OD PRESSURE SWITCH OPEN
Refer to the DTC EVENT DATA recorded earlier for P0871.
Did the OD Pressure Switch read OPEN?
YES >>Go To 10
NO >>Go To 15
10. LOW LINE PRESSURE
Refer to the DTC EVENT DATA recorded earlier and 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 the fluid level. Check the Primary Oil Filter seal for a split, crack, or improperly installed. If the fluid level and filter are OK, check the Main Regulator Valve in the Oil Pump.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Go To 11
11. (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO ANOTHER CIRCUIT
Turn the ignition off to the lock position.
Disconnect all PCM harness connectors.
Disconnect the Transmission Solenoid/TRS Assembly harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the (T9) OD 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 (T9) OD Pressure Switch Sense circuit and any other circuit(s) in the Transmission Solenoid/TRS Assembly harness connector?
YES >>Repair the (T9) OD Pressure Switch Sense circuit for a short to another circuit(s).
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Go To 12
12. CHECK TO SEE IF DTC RESETS
Reconnect all previously disconnected connectors.
With the scan too, erase transmission DTCs. Test drive the vehicle, use the DTC EVENT DATA recorded earlier to help duplicate the conditions when the DTC originality set.
Does the DTC P0871 reset?
YES >>Go To 13
NO >>Go To 22
13. POWERTRAIN CONTROL MODULE
Remove the Transmission Control Relay Operate the vehicle in Drive.
Is the transmission slipping while in Drive?
YES >>Go To 14
NO >>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. If no problems are found, replace the PCM. With the scan tool, perform QUICK LEARN.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
14. INTERNAL TRANSMISSION
Perform an Air Check Transmission Clutch Operation procedure.
NOTE: The OD/Rev piston contains a small bleed orifice, a small amount of leakage between the OD and Reverse hydraulic clutch circuits is considered normal.
Is there excessive air leakage in any clutch circuit?
YES >>Check the OD/Rev piston seals and bleed orifice, reaction shaft support seal rings, dribbler orifice assemblies in the reaction shaft support and for poor machine on the pump valve body faces.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Repair the Valve Body. Check the OD Accumulator piston and seals, OD bleed orifice, and No.6 check ball cuts or damage. If no problems are found in the Valve Body, replace the Transmission Solenoid/ TRS Assembly
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
15. 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 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 OD.
With the scan tool, monitor the OD Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.
Did the state of the OD Pressure Switch change from OPEN to CLOSED while pressing the Test button?
YES >>Go To 16
NO >>Go To 18
16. NO. 4 AND/OR NO. 6 CHECK BALL CUT OR DAMAGED
With the scan tool, erase previously stored DTC's and test drive the vehicle, use the DTC EVENT DATA to help duplicate the conditions when the DTC originality set. Note any DTCs that may set.
Remove the Transmission Valve Body.
Check the No. 4 and No. 6 Check Balls for cuts or damage.
Is the No. 4 and/or No. 6 Check Ball cut or damaged?
YES >>Replace the No. 4 and/or No. 6 Check Ball and check for clutch debris in the transmission oil pan. If there is excessive debris, perform internal repairs to the OD Clutch Assembly.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Go To 17
17. TRANSMISSION SOLENOID/TRS ASSEMBLY
Did the DTC P0871 reset during the test drive in the previous step?
YES >>Replace the Transmission Solenoid/TRS Assembly.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Go To 22
18. (T9) OD PRESSURE SWITCH SENSE CIRCUIT OPEN
Turn the ignition off to the lock position.
Disconnect the PCM C4 harness connector and connect Miller tool #8815.
Disconnect the Transmission Solenoid /TRS Assembly harness connector
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 (T9) OD Pressure Switch Sense circuit from the appropriate terminal of Miller tool #8815 to the Solenoid/TRS Assembly harness connector.
Is the resistance above 5.0 ohms?
YES >>Repair the (T9) OD Pressure Switch Sense circuit for an open.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Go To 19
19. (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
Measure the resistance between ground and the (T9) OD Pressure Switch Sense circuit.
Is the resistance below 5.0 ohms?
YES >>Repair the (T9) OD Pressure Switch Sense circuit for a short to ground.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Go To 20
20. WIRING AND CONNECTORS
Using the schematics as a guide, inspect the wiring and connectors. 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 21
21. POWERTRAIN CONTROL MODULE
Reconnect all previously disconnected connectors.
Make sure all DTC EVENT DATA is recorded. With the scan tool, erase previously stored DTC's and test drive the vehicle, use the DTC EVENT DATA to help duplicate the conditions when the DTC originality set.
Does the DTC P0871 reset?
YES >>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. If no problems are found, replace the PCM. With the scan tool, perform QUICK LEARN.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Go To 22
22. 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 DTC EVENT DATA to help identify the conditions in which the DTC was set.
Where there any problems found?
YES >>Repair as necessary.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests
NO >>Test Complete.