Advanced Diagnostics

Advanced Diagnostics - DTC P0843: Open in Transmission Fluid Pressure Switch A (2nd Clutch) Circuit, or Transmission Fluid Pressure Switch A (2nd Clutch) Stuck OFF










General Description
Transmission fluid pressure switch A (2nd clutch) is installed in the hydraulic pressure circuit to the 2nd clutch. When hydraulic pressure is supplied to the 2nd clutch, the switch is turned on. When hydraulic pressure is not supplied to the 2nd clutch, the switch is turned off. The signal from transmission fluid pressure switch A (2nd clutch) is input to the powertrain control module (PCM). The PCM detects the hydraulic pressure supply conditions at the gear change to 2nd gear (1st -> 2nd) to reduce the shock that occurs at the gear change. If transmission fluid pressure switch A (2nd clutch) is off while driving the vehicle with the rotation speed ratio of the input/output pulses is that of the 2nd gear ratio, the PCM detects a transmission fluid pressure switch A (2nd clutch) failure and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
The input signal from transmission fluid pressure switch A (2nd clutch) to the PCM is high when driving in 2nd gear.

Driving Pattern
1. Start the engine.
2. Drive the vehicle in 2nd gear for at least 4 seconds.

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.