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DTC Troubleshooting: P0843 (25)

DTC P0843:
 2nd Clutch Transmission Fluid Pressure Switch (Open or Stuck OFF)
  1. Clear the DTC with the HDS.
  1. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).
  1. Shift into 2nd gear, and verify Shift Control display in the HDS:
    • Seven-position transmission: Shift to 2 while pressing the brake pedal, and verify with the HDS in the A/T data list that the Shift Control indicates 2nd.
    • Five-position transmission: Shift to S while pressing the brake pedal, upshift to 2nd gear by pulling the paddle shifter + (upshift switch), and verify with the HDS in the A/T data list that the Shift Control indicates 2nd.
  1. 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 .
  1. Test-drive the vehicle:
    • Seven-position transmission: Drive the vehicle in 2 for at least 2 seconds, then slow down to a stop.
    • Five-position transmission: Drive the vehicle in 2nd gear in the sequential shift mode in S for at least 2 seconds, then slow down to a stop.
  1. Monitor the OBD status for P0843 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
Does the HDS indicate FAILED?
YES -
Go to Step 8 .
NO -
Intermittent failure, the system is OK at this time. Check for poor connections and loose terminals at the 2nd clutch transmission fluid pressure switch and the PCM. If the HDS indicates NOT COMPLETED, return to Step 5 and recheck.
Is the 2nd clutch pressure within the service limits?
YES -
Go to Step 8 .
NO -
Repair shift valves A, B, and C, and related hydraulic circuit, or replace the transmission, then go to Step 22 .
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the 2nd clutch transmission fluid pressure switch connector.
  1. Turn the ignition switch to ON (II).
  1. Measure the voltage between the 2nd clutch transmission fluid pressure switch connector terminal and body ground.
Is there about 5 V?
YES -
NO -
Go to Step 12 .
  1. Turn the ignition switch to LOCK (0).
  1. Jump the SCS line with the HDS.
  1. Disconnect PCM connector B (49P).

  1. Check for continuity between PCM connector terminal B8 and the 2nd clutch transmission fluid pressure switch connector terminal.
Is there continuity?
YES -
Go to Step 16 .
NO -
Repair open in the wire between PCM connector terminal B8 and the 2nd clutch transmission fluid pressure switch, then go to Step 22 .
  1. Reconnect all connectors.
  1. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).
  1. Test-drive the vehicle:
    • Seven-position transmission: Drive the vehicle in 2nd gear in D for at least 2 seconds, then press the accelerator pedal so that the transmission upshifts into 4th gear, and drive in 4th gear for at least 2 seconds. Slow down and stop the wheels.
    • Five-position transmission: Drive the vehicle in 2nd gear in the sequential shift mode in S for at least 2 seconds, then upshift to 4th gear by pulling the paddle shifter + (upshift switch), and drive in 4th gear for at least 2 seconds. Slow down and stop the wheels.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0843 indicated?
YES -
If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to Step 1 .
NO -
Go to Step 21 .
  1. Monitor the OBD status for P0843 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
Does the HDS indicate PASSED?
YES -
If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other DTCs were indicated on Step 20 , go to the indicated DTC's troubleshooting.■
NO -
Check for poor connections and loose terminals at the 2nd clutch transmission fluid pressure switch and the PCM. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to Step 1 . If the HDS indicates NOT COMPLETED, return to Step 19 and recheck.
  1. Reconnect all connectors.
  1. Clear the DTC with the HDS.
  1. Start the engine, and warm it up to normal operating temperature (the radiator fan comes on).
  1. Test-drive the vehicle:
    • Seven-position transmission: Drive the vehicle in 2nd gear in D for at least 2 seconds, then press the accelerator pedal so that the transmission upshifts into 4th gear, and drive in 4th gear for at least 2 seconds. Slow down and stop the wheels.
    • Five-position transmission: Drive the vehicle in 2nd gear in the sequential shift mode in S for at least 2 seconds, then upshift to 4th gear by pulling the paddle shifter + (upshift switch), and drive in 4th gear for at least 2 seconds. Slow down and stop the wheels.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0843 indicated?
YES -
Check for poor connections and loose terminals at the 2nd clutch transmission fluid pressure switch and the PCM, then go to Step 1 .
NO -
Go to Step 27 .
  1. Monitor the OBD status for P0843 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
Does the HDS indicate PASSED?
YES -
Troubleshooting is complete. If any other DTCs were indicated on Step 26 , go to the indicated DTC's troubleshooting.■
NO -
Check for poor connections and loose terminals at the 2nd clutch transmission fluid pressure switch and the PCM, then go to Step 1 . If the HDS indicates NOT COMPLETED, return to Step 25 and recheck.