Advanced Diagnostics

Advanced Diagnostics - DTC P0873: Open in 4th Clutch Transmission Fluid Pressure Switch Circuit, or 4th Clutch Transmission Fluid Pressure Switch Stuck OFF










General Description
The 4th clutch transmission fluid pressure switch is installed in the hydraulic pressure circuit to the 4th clutch. When hydraulic pressure is supplied to the 4th clutch, the switch is turned ON. When hydraulic pressure is not supplied to the 4th clutch, the switch is turned OFF. The signal from the 4th clutch transmission fluid pressure switch is input to the powertrain control module (PCM). The PCM detects the hydraulic pressure supply conditions at the gear change to 4th gear (3rd --> 4th, 5th --> 4th) to reduce the shock that occurs at the gear change. If the 4th clutch transmission fluid pressure switch is OFF while driving the vehicle with the rotation speed ratio of the input/output pulses is that of 4th gear, the PCM detects a 4th clutch transmission fluid pressure switch failure and stores a DTC.

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






Enable Conditions






Malfunction Threshold
The input signal from the 4th clutch transmission fluid pressure switch to the PCM is high when driving in 4th gear.

Driving Pattern
1. Start the engine.
2. Drive the vehicle in 4th gear for at least 2 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, a Confirmed DTC and the freeze data are stored. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.