DTC Troubleshooting
DTC Troubleshooting: P0843 (25)
DTC P0843:
Open in Transmission Fluid Pressure Switch A (2nd Clutch) Circuit, or Transmission Fluid Pressure Switch A (2nd Clutch) Stuck OFF
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot with the HDS, and review General Troubleshooting Information Reading and Clearing Diagnostic Trouble Codes.
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. Shift to S while pressing the brake pedal, upshift to 2nd gear by the paddle shifter + (upshift switch), and verify with the HDS in the A/T Data List that the Shift Control indicates 2nd.
5. 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 6.
NO -
Go to step 8.
6. Test-drive the vehicle in 2nd gear in D for at least 2 seconds. Slow down, and stop the wheels.
7. Monitor the OBD status for P0843 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 and loose terminals at transmission fluid pressure switch A (2nd clutch) 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 transmission fluid pressure switch A (2nd clutch) connector.
10. Connect a jumper wire between the transmission fluid pressure switch A (2nd clutch) 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 2nd Pressure Switch signal with the HDS in the A/T Data List.
Is the 2nd Pressure Switch ON?
YES -
Go to step 13.
NO -
Go to step 16.
13. Reconnect the transmission fluid pressure switch A (2nd clutch) connector.
14. Clear the DTC with the HDS.
15. Measure the 2nd clutch pressure A/T Pressure Test.
Is the 2nd clutch pressure within the service limit?
YES -
Replace transmission fluid pressure switch A (2nd clutch) Transmission Fluid Pressure Switch A (2nd Clutch) Replacement, then go to step 20.
NO -
Replace shift valves A, B, and C, and related hydraulic circuit, or replace the transmission, then go to step 23.
16. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
17. Jump the SCS line with the HDS.
18. Disconnect PCM connector C (49P).
19. Check for continuity between PCM connector terminal C27 and the transmission fluid pressure switch A (2nd clutch) connector terminal.
Is there continuity?
YES -
Go to step 27.
NO -
Repair an open in the wire between PCM connector terminal C27 and transmission fluid pressure switch A (2nd clutch), then go to step 20.
20. Reconnect all connectors.
21. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
22. Clear the DTC with the HDS.
23. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).
24. Test-drive the vehicle in 2nd gear in D for at least 2 seconds, then press the accelerator pedal so that the transmission upshifts to 3rd gear. Drive the vehicle 3rd gear for at least 2 seconds in each gear. Slow down, and stop the wheels.
25. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0843 indicated?
YES -
Check for poor connections or loose terminals between transmission fluid pressure switch A (2nd clutch) and the PCM, then go to step 1.
NO -
Go to step 26.
26. 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 in step 25, go to the indicated DTC's troubleshooting.�
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals between transmission fluid pressure switch A (2nd clutch) and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, go to step 23.
27. Reconnect all connectors.
28. Update the PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good PCM.
29. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).
30. Test-drive the vehicle in 2nd gear in D for at least 2 seconds, then press the accelerator pedal so that the transmission upshifts to 3rd gear. Drive the vehicle 3rd gear for at least 2 seconds in each gear. Slow down, and stop the wheels.
31. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0843 indicated?
YES -
Check for poor connections or loose terminals between transmission fluid pressure switch A (2nd clutch) and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 29. If the PCM was substituted, go to step 1.
NO -
Go to step 32.
32. 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 in step 31, go to the indicated DTC's troubleshooting.�
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals between transmission fluid pressure switch A (2nd clutch) and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 29. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 29.