DTC Troubleshooting

DTC Troubleshooting: P0873

DTC P0873: 4th Clutch Transmission Fluid Pressure Switch (Open or Stuck OFF)

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

1. Clear the DTC with the HDS.

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

3. Test-drive the vehicle in 4th gear in the sequential SportShift mode in S, and verify with the HDS in the A/T Data List that the Shift Command indicates 4th.

4. 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 5.

NO - Go to step 7.


5. Test-drive the vehicle in 4th gear in the sequential SportShift mode in S for at least 2 seconds, then slow down to a stop.

6. Monitor the OBD STATUS for P0873 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?
YES - Go to step 7.

NO - 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, return to step 5 and recheck.


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

Is the 4th clutch pressure within the service limits?
YES - Go to step 8.

NO - Repair shift valves B, C, and E, and related hydraulic circuit, or replace the transmission, then go to step 18.


8. Turn the ignition switch to LOCK (0).

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

10. Turn the ignition switch to ON (II).

11. Measure the voltage between the 4th clutch transmission fluid pressure switch connector terminal and body ground.

Is there about 5 V?
YES - Replace the 4th clutch transmission fluid pressure switch, 4th Clutch Transmission Fluid Pressure Switch Replacement then go to step 19.

NO - Go to step 12.






12. Measure the voltage between PCM connector terminal C20 and body ground.

Is there about 5 V?
YES - Repair an open in the wire between PCM connector terminal C20 and the 4th clutch transmission fluid pressure switch, then go to step 18.

NO - Go to step 13.






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

14. Update the A/T software in the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Reading and Clearing Diagnostic Trouble Codes

15. Test-drive the vehicle in 4th gear in the sequential SportShift mode in S for at least 2 seconds, then upshift to 5th gear, and drive in 5th gear for at least 2 seconds. Slow down and stop the wheels.

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

Is DTC P0873 indicated?
YES - If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the PCM was substituted, go to step 1.

NO - Go to step 17.


17. 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. Service and Repair If any other Pending or Confirmed DTCs were indicated on step 16, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at the 4th clutch transmission fluid pressure switch and the PCM. If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, return to step 15 and recheck.


18. Clear the DTC with the HDS.

19. Test-drive the vehicle in 4th gear in the sequential SportShift mode in S for at least 2 seconds, then upshift to 5th gear, and drive in 5th gear for at least 2 seconds. Slow down and stop the wheels.

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

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

NO - Go to step 21.


21. 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 on step 20, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at the 4th clutch transmission fluid pressure switch and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, return to step 19 and recheck.