Theory Of Operation

WARNING: This page is about a different car, the 2016 Dodge Charger and 2015 Dodge Charger. However, it is still accessible from the selected car via links, so may be relevant.

The Transmission Control Module (TCM) constantly calculates the transmission ratio based on the input speed sensor 1 and 2 (N2-N3) signals and the calculated transmission output shaft speed. The intent of this diagnostic is to detect if the transmission is trying to mechanically shift into a different gear than the TCM intends.

The intent of this diagnostic is to detect one of the following conditions:

An implausible gear ratio.
During a gear shift request, the transmission hydraulically or mechanically shifted into a gear other than what the TCM intended.

NOTE:

The transmission control module is programmed to immediately place the transmission into neutral if P0730 or P1731 codes are set. These codes indicate that the transmission experienced an unknown or incorrect gear ratio. Placing the transmission in neutral prevents potential catastrophic failure. When this occurs, the transmission will remain in neutral until the vehicle slows to 29 Km/h (18 mph).