P0871 Jeep OBD Code
OD PRESSURE SWITCH RATIONALITY
For a complete wiring diagram Refer to Section 8W.
Theory of Operation
The Transmission system uses three pressure switches to monitor the fluid pressure in the LR, 2/4, and OD elements. The pressure switches are continuously monitored for the correct states in
each gear. Normal operation will be experienced if no other codes are present. Transmission Control System will ignore the code. Limp-in condition will only occur if DTC P0871 is present with a DTC P0706.
- When Monitored:
Whenever the engine is running.
- Set Condition:The DTC is set if one of the pressure switches are open or closed at the wrong time in a given gear. If the problem is identified for 3 successive key starts, the transmission will go into limp-in
mode and the MIL will turn on after 10 seconds of vehicle operation.
| Possible Causes |
| RELATED TIPM TCM POWER INPUT DTCS PRESENT |
| LOSS OF PRIME DTC PRESENT |
| (T9) OD PRESSURE SWITCH SENSE CIRCUIT OPEN |
| (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND |
| (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE |
| TRANSMISSION SOLENOID/PRESSURE SWITCH ASSEMBLY |
| POWERTRAIN CONTROL MODULE |
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding.
(Refer to 21 – TRANSMISSION/TRANSAXLE/AUTOMATIC- 42RLE – STANDARD PROCEDURE)
PRESSURE SWITCH STATES
| GEAR | L/R | 2/4 | OD |
| R | OPEN | OPEN | OPEN |
| P/N | CLOSED | OPEN | OPEN |
| 1st | CLOSED | OPEN | OPEN |
| 2nd | OPEN | CLOSED | OPEN |
| D | OPEN | OPEN | CLOSED |
| OD | OPEN | CLOSED | CLOSED |
Diagnostic Test
1. CHECK FOR TIPM TCM POWER INPUT DTCS
With the scan tool under TIPM, check for TCM Power Input DTCs.
Are there any TIPM TCM Power Input DTCs present?
Yes
- Refer to the Transmission category and perform the appropriate diagnostic procedure.
No
- Go To 2
2. CHECK FOR LOSS OF PRIME DTC
With the scan tool, check for other Transmission DTCs.
Is the DTC P0944 present also?
Yes
- Refer to the Transmission category and perform the appropriate diagnostic procedure.
No
- Go To 3
3. CHECK TO SEE IF P0841 IS CURRENT
With the scan tool, view DTCs.
Is the status Active for this DTC or is the STARTS SINCE SET counter 2 or less?
Yes
- Go To 4
No
- Go To 8
4. 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 and the Electronic Transmission Adapter kit.
- Ignition on, engine not running.
- With the Transmission Simulator, turn the Pressure Switch selector 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 OD Pressure Switch state change?
Yes
- Replace the Transmission Solenoid/Pressure Switch Assembly per the Service Information.
- Perform 42RLE TRANSMISSION VERIFICATION TEST(Refer to 21 – TRANSMISSION/TRANSAXLE/AUTOMATIC – 42RLE – STANDARD PROCEDURE)
No
- Go To 5
5. (T9) OD PRESSURE SWITCH SENSE CIRCUIT OPEN
- Turn the ignition off to the lock position.
- Disconnect the PCM C4 harness connector.
- Disconnect the Transmission Solenoid/Pressure Switch 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 between the Transmission Solenoid/Pressure Switch Assembly harness connector and the appropriate terminal of Miller tool #8815.
Is the resistance above 5.0 ohms?
Yes
- Repair the (T9) OD Pressure Switch Sense circuit for an open.
- Perform 42RLE TRANSMISSION VERIFICATION TEST(Refer to 21 – TRANSMISSION/TRANSAXLE/AUTOMATIC – 42RLE – STANDARD PROCEDURE)
No
- Go To 6
6. (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 42RLE TRANSMISSION VERIFICATION TEST(Refer to 21 – TRANSMISSION/TRANSAXLE/AUTOMATIC – 42RLE – STANDARD PROCEDURE)
No
- Go To 7
7. (T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
- Ignition on, engine not running.
- With the scan tool under TIPM, actuate the Transmission.
- Measure the voltage of the (T9) OD Pressure Switch Sense circuit.
Is the voltage above 0.5 volts?
Yes
- Repair the (T9) OD Pressure Switch Sense circuit for a short to voltage.
- Perform 42RLE TRANSMISSION VERIFICATION TEST(Refer to 21 – TRANSMISSION/TRANSAXLE/AUTOMATIC – 42RLE – STANDARD PROCEDURE)
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 and program the PCM per the Service Information. With the scan tool, perform QUICK LEARN.
- Perform 42RLE TRANSMISSION VERIFICATION TEST(Refer to 21 – TRANSMISSION/TRANSAXLE/AUTOMATIC – 42RLE – STANDARD PROCEDURE)
8. INTERMITTENT WIRING AND CONNECTORS
- The conditions necessary to set the 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.
Were there any problems found?
Yes
- Repair as necessary.
- Perform 42RLE TRANSMISSION VERIFICATION TEST(Refer to 21 – TRANSMISSION/TRANSAXLE/AUTOMATIC – 42RLE – STANDARD PROCEDURE)
No
- Test Complete.