Theory Of Operation

WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

A shift cable is connected between the Shift Lever and the Transmission Range Switch (TRS) located in the Transmission. When the shift lever is moved, the cable moves the TRS. The TRS contains five switches. The combination of open or closed switches is used by the TCM to determine the desired gear selection. The T41 (C1), T42 (C2), T3 (C3), T1 (C4), T4 (C5) Signal circuits communicate the TRS position to the Transmission Control Module (TCM). Each circuit is hard wired between the TCM and the TRS switch.

The combination of open or closed TRS switches is called a PRNDL code. There are 12 valid PRNDL codes: two for neutral, one for each of the five gear positions, and five temporary (transition zone) PRNDL codes. The remainder of the PRNDL codes should never occur, these are called invalid codes.