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 the General Troubleshooting Information Reading and Clearing Diagnostic Trouble Codes.
1. Turn the ignition switch to ON (II).
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 check if the Shift Control indicates 2 in the A/T Data List with the HDS.
5. Check the 2nd Pressure Switch in the A/T Data List with the HDS.
Is the 2nd Pressure Switch ON?
YES -
Go to step 6.
NO -
Go to step 8.
6. Test-drive the vehicle in 2nd gear with the shift lever in D for at least 2 seconds.
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 or loose terminals between 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).
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).
12. Check the 2nd Pressure Switch in the A/T Data List with the HDS.
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 21.
NO -
Repair shift valves A, B, and C, and the related hydraulic circuit, or replace the transmission, then go to step 24.
16. Remove the jumper wire, then measure the voltage between the transmission fluid pressure switch A (2nd clutch) connector terminal and body ground.
Is there about 5V?
YES -
Replace transmission fluid pressure switch A (2nd clutch) Transmission Fluid Pressure Switch A (2nd Clutch) Replacement, then go to step 28.
NO -
Go to step 17.
17. Turn the ignition switch to LOCK (0).
18. Jump the SCS line with the HDS.
19. Disconnect PCM connector B (49P).
20. Check for continuity between PCM connector terminal B8 and the transmission fluid pressure switch A (2nd clutch) connector terminal.
Is there continuity?
YES -
Go to step 28.
NO -
Repair an open in the wire between PCM connector terminal B8 and transmission fluid pressure switch A (2nd clutch), then go to step 21.
21. Reconnect all connectors.
22. Turn the ignition switch to ON (II).
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 2nd gear with the shift lever in D for at least 2 seconds, then drive in 4th gear for at least 2 seconds.
26. 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 27.
27. 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 26, 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 24.
28. Reconnect all connectors.
29. Update the PCM if it does not have the latest software ECM/PCM Update (M/T), or substitute a known-good PCM.
30. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).
31. Test-drive the vehicle in 2nd gear with the shift lever in D for at least 2 seconds, then drive in 4th gear for at least 2 seconds.
32. 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 30. If the PCM was substituted, go to step 1.
NO -
Go to step 33.
33. 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 32, 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 30. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 30.