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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 33 (Automatic Transaxle - 4T65-E - Removal & Installation, Service, Overhaul, Troubleshooting & Diagnosis) >> Description And Operation >> Automatic Transmission Hydraulic Diagrams >> Park or Neutral - Engine Running (Park - With Touch Activated Power) >> Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly (34)

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly (34)

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The automatic transmission fluid pressure (TFP) switch is attached to the valve body and consists of one fluid pressure switch that monitors TCC release pressure. This switch is used as a diagnostic tool to confirm that the TCC is actually off when it has been commanded off by the PCM.

The TCC release switch is a normally closed pressure switch. A normally closed switch allows current to flow from the positive contact through the switch to ground when no fluid is present. Fluid pressure moves the diaphragm to disconnect the positive and ground contacts, opening the switch and stopping current flow. This change in switch state electronically signals the PCM that the TCC is released.