DTC Troubleshooting

DTC Troubleshooting: P0873 (27)

DTC P0873: Open in 4th Clutch Transmission Fluid Pressure Switch Circuit, or 4th Clutch Transmission Fluid Pressure Switch Stuck OFF

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot with the HDS, and review General Troubleshooting Information. How to Troubleshoot A/T Systems

1. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

2. Clear the DTC with the HDS.

3. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).

4. Test-drive the vehicle in 5th gear in D, and verify with the HDS in the A/T Data List that the Shift Control indicates 4th.

5. Check the 4th Pressure Switch signal with the HDS in the A/T Data List.

Is the 4th Pressure Switch ON?
YES - Go to step 6.

NO - Go to step 8.


6. Test-drive the vehicle in 4th gear in D for at least 2 seconds, then slow down to a stop.

7. Monitor the OBD status for P0873 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?
YES - Go to step 8.

NO - If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the 4th clutch transmission fluid pressure switch and the PCM. If the HDS indicates NOT COMPLETED, go to step 6.


8. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

9. Disconnect the 4th clutch transmission fluid pressure switch connector.

10. Connect a jumper wire between the 4th clutch transmission fluid pressure switch connector terminal and body ground.

11. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.






12. Check the 4th pressure switch signal with the HDS in the A/T Data List.

Is the 4th Pressure Switch ON?
YES - Go to step 13.

NO - Go to step 16.


13. Reconnect the 4th clutch transmission fluid pressure switch connector.

14. Clear the DTC with the HDS.

15. Measure the 4th clutch pressure. A/T Pressure Test

Is the 4th clutch pressure within the service limits?
YES - Replace the 4th clutch transmission fluid pressure switch, 4th Clutch Transmission Fluid Pressure Switch Replacement then go to step 21.

NO - Repair shift valves A, B, C, and D, and related hydraulic circuit, or replace the transmission, then go to step 24.


16. Remove the jumper wire, then measure the voltage between the 4th clutch transmission fluid pressure switch connector terminal and body ground.

Is there battery voltage?
YES - Go to step 28.

NO - Go to step 17.






17. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

18. Jump the SCS line with the HDS.

19. Disconnect PCM connector C (49P).

20. Check for continuity between PCM connector terminal C37 and the 4th clutch transmission fluid pressure switch connector terminal.

Is there continuity?
YES - Go to step 28.

NO - Repair open in the wire between PCM connector terminal C37 and the 4th clutch transmission fluid pressure switch, then go to step 21.






21. Reconnect all connectors.

22. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

23. Clear the DTC with the HDS.

24. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).

25. Test-drive the vehicle in 4th gear in D for at least 2 seconds, then press the accelerator pedal so that the transmission upshifts to 5th gear, and drive for at least 2 seconds. Slow down and stop the wheels.

26. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0873 indicated?
YES - Check for poor connections or loose terminals between the 4th clutch transmission fluid pressure switch and the PCM, then go to step 1.

NO - Go to step 27.


27. Monitor the OBD status for P0873 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED?
YES - Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 26, go to the indicated DTC's troubleshooting.

NO - If the HDS indicates FAILED, check for poor connections or loose terminals between the 4th clutch transmission fluid pressure switch and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, go to step 24.


28. Reconnect all connectors.

29. Update the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Initial Inspection and Diagnostic Overview

30. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).

31. Test-drive the vehicle in 4th gear in D for at least 2 seconds, then press the accelerator pedal so that the transmission upshifts to 5th gear, and drive for at least 2 seconds. Slow down and stop the wheels.

32. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0873 indicated?
YES - Check for poor connections or loose terminals between the 4th clutch transmission fluid pressure switch and the PCM. If the PCM was updated, substitute a known-good PCM, Initial Inspection and Diagnostic Overview then go to step 30. If the PCM was substituted, go to step 1.

NO - Go to step 33.


33. Monitor the OBD status for P0873 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED?
YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. PCM Replacement If any other Pending or Confirmed DTCs were indicated in step 32, go to the indicated DTC's troubleshooting.

NO - If the HDS indicates FAILED, check for poor connections or loose terminals between the 4th clutch transmission fluid pressure switch and the PCM. If the PCM was updated, substitute a known-good PCM, Initial Inspection and Diagnostic Overview then go to step 30. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 30.