Theory Of Operation

The purpose of this diagnostic is to detect a potential open circuit or short to ground at the Torque Converter Clutch (TCC) Variable Force Solenoid (VFS) low side driver circuit.

The Transmission Control System uses electronically controlled solenoids that allow hydraulic fluid to be applied to various friction elements (clutches), which enables the gear requested. The continuity of each solenoid circuit is periodically tested. Each inactive solenoid is turned on for a few milliseconds, then off. Each active solenoid is turned off for a few milliseconds, then on. This pulsing of voltage to the solenoid causes an inductive spike which can be sensed by the Transmission Control System. If an inductive spike is not sensed by the Transmission Control System during the continuity check, it is tested again. If the test fails three consecutive times, the appropriate Diagnostic Trouble Code (DTC) is set.

The TCC VFS solenoid has variable flow characteristics that need to be recognized by the Powertrain Control Module (PCM) for proper TCC operation. This is known as the PI Data. When replacing the TCC VFS or the valve body, the 2D BAR code on the body of the solenoid must be scanned. The scanned information must then be entered into the scan tool, which is then used to upload the information into the PCM. If replacing the PCM, use the scan tool to copy the PI information from the PCM being replaced, and uploading it to the new PCM. If the PCM being replaced is non-responsive, the PI Data can be retrieved from a 2D bar code on the right side exterior of the transmission case. The data must be entered into the scan tool in order to upload the information to the PCM. In the event that the exterior BAR code is missing, or it is suspected that the valve body or TCC VFS has been replaced without uploading the correct PI Data into an existing PCM, the transmission oil pan must be removed to retrieve the information from the 2D bar code on the body of the TCC VFS solenoid.