Transmission Fluid Pressure Manual Valve Position Switch ASSY

The Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) assembly is attached to the valve body. This assembly contains six fluid pressure switches and the Automatic Transmission Fluid Temperature sensor.

Five of the fluid pressure switches are normally open. These are used to indicate the position of the manual valve. The PCM uses this information to control line pressure, TCC apply and release and shift solenoid operation.

The release pressure switch is used as a diagnostic tool to confirm that the TCC is actually OFF when it has been commanded OFF by the PCM. This switch is normally closed.

Each fluid pressure switch produces either an open or a ground to the PCM depending on the presence of fluid pressure at the switches. The sequence of open and closed switches produces a combination of voltage readings. The PCM monitors these reading.

The PCM measures PSA signal voltage from each pin to ground and compares the voltage to a PSA combination chart stored in the PCM memory. If the PCM does not recognize the switch sequence, a diagnostic code will be as a result. A diagnostic code may also set if the PSA switch sequence indicates a gear range selection that conflicts with other sensory inputs to the PMC.

Valid combinations for Circuits A, B,and C are shown in the figure. ON means that the switch is grounded with a resistance less than 50 ohms at 0 volts; OFF means that the switch is open with a resistance greater than 50K ohms at 12 volts.

Note that resistance should be measured with the engine running. When the transmission's pass through connector is disconnected from the vehicle harness while the engine is running, multiple diagnostic codes will set. Clear these codes when you are finished with this procedure.