Transmission Fluid Pressure Manual Valve Position Switch

The Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) is attached to the valve body, and consists of six fluid pressure switches. Three of the fluid pressure switches (PND4, Low, and Reverse) are normally open, while the other three (D3, D2, and TCC Release) are normally closed. These six switches indicate the position of the manual valve. The Powertrain Control Moduel (PCM) uses this information in order to control line pressure, Torque Converter Clutch (TCC) apply, and release and shift solenoid operation.

The Release pressure switch is a normally closed pressure switch. This switch is used as a diagnostic tool in order to confirm that the TCC is actually Off when the PCM issues the command to turn the switch Off.





Each fluid pressure switch produces either an Open or a Ground to the PCM depending upon the presence of fluid pressure at the switches. The sequence of open and closed switches produces a combination of voltage readings that are monitored by the PCM. The PCM measures the TFP Val. Position Sw. signal voltage from each pin to ground and compares this voltage to a combination chart which is stored in PCM memory. If the PCM does not recognize the switch sequence, then a diagnostic code will be set as a result. A diagnostic code may also be set if the TFP Val. Position Sw. sequence indicates a gear range selection that conflicts with other sensory inputs to the PCM.

Resistance should be measured with the engine running. When the transmission pass-through connector is disconnected from the vehicle harness and the engine is running, then multiple diagnostic codes will be set. Clear these codes when you have finished with this procedure.