DTC Troubleshooting

DTC Troubleshooting: P0843

DTC P0843: Transmission Fluid Pressure Switch A (2nd Clutch) (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. Shift the shift lever into S while pressing the brake pedal, upshift to 2nd gear by pressing the paddle shifter + (upshift switch), and verify that the shift command indicates 2nd in the A/T Data List.

4. Check the 2nd Pressure Switch signal with the HDS in the A/T Data List.

Is the 2nd Pressure Switch ON?
YES - Go to step 5.

NO - Go to step 7.


5. Test-drive the vehicle in 2nd 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 P0843 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 and loose terminals at the transmission fluid pressure switch A (2nd clutch) and the PCM. If the HDS indicates NOT COMPLETED, return to step 5 and recheck.


7. Measure the 2nd clutch pressure. A/T Pressure Test

Is the 2nd clutch pressure within the service limits?
YES - Go to step 8.

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


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

9. Disconnect the transmission fluid pressure switch A (2nd clutch) connector.

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

11. Measure the voltage between the transmission fluid pressure switch A (2nd clutch) connector terminal and body ground.

Is there about 5 V?
YES - Replace the transmission fluid pressure switch A (2nd clutch), Transmission Fluid Pressure Switch A (2nd Clutch) Replacement then go to step 18.

NO - Go to step 12.






12. Measure the voltage between PCM connector terminal C11 and body ground.

Is there about 5 V?
YES - Repair an open in the wire between PCM connector terminal C11 and the transmission fluid pressure switch A (2nd clutch), then go to step 18.

NO - Go to step 13.






13. Connect the transmission fluid pressure switch A (2nd clutch) 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 2nd gear in the sequential SportShift mode in S for at least 2 seconds, then upshift to 4th gear, and drive in 4th gear for at least 2 seconds. Slow down and stop the wheels.

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

Is DTC P0843 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 P0843 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 transmission fluid pressure switch A (2nd clutch) 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 2nd gear in the sequential SportShift mode in S for at least 2 seconds, then upshift to 4th gear, and drive in 4th gear for at least 2 seconds. Slow down and stop the wheels.

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

Is DTC P0843 indicated?
YES - Check for poor connections and loose terminals at the transmission fluid pressure switch A (2nd clutch) and the PCM, then go to step 1.

NO - Go to step 21.


21. Monitor the OBD STATUS for P0843 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 transmission fluid pressure switch A (2nd clutch) and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, return to step 19 and recheck.