Transmission Range Indicator

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.

The electronic gear selector indicator gives an indication to the vehicle operator of the transmission gear that has been selected with the automatic transmission gear selector lever. This indicator is controlled by the Instrument Panel Cluster (IPC) circuit board based upon cluster programming. The IPC circuitry automatically configures itself for the proper transmission type based upon the hard wired transmission range sensor mux circuit input to the IPC.

The gear selector indicator information is displayed by the odometer/trip odometer Liquid Crystal Display (LCD) unit soldered onto the IPC electronic circuit board, and the LCD will not display the gear selector indicator information after the ignition switch is turned to the OFF position. Each time the IPC is disconnected from battery current for more than about five minutes, it must configure itself for the automatic transmission type that is in the vehicle once it is reconnected to battery current. The IPC circuitry configures the gear selector indicator based upon the following inputs from the transmission range sensor:

Open Circuit - If the IPC is configured for an automatic transmission and the transmission range sensor mux circuit is open, the IPC circuitry controls the gear selector indicator display based upon an electronic selected gear message received from the Transmission Control Module (TCM) over the Controller Area Network (CAN) data bus. If the Transmission Range Sensor (TRS) mux circuit is open and no electronic selected gear messages are received from the TCM within two seconds, the IPC circuitry will not display any gear selector position until the condition is resolved or until the ignition switch is turned to the OFF position, whichever occurs first.
Resolved Circuit - If the transmission range sensor mux circuit is resolved, the cluster circuitry controls the gear selector indicator display based upon the resistance value of the hard wired input from the TRS. If the IPC is configured for an automatic transmission with a TRS input and detects a short to ground or an open in the TRS mux input, the IPC circuitry will not display any gear selector position in the LCD display. The short-to-ground and open circuit conditions for the LCD display will continue until the condition is resolved or until the ignition switch is turned to the OFF position, whichever occurs first.

On vehicles with a TCM, the TCM continually monitors the TRS, then sends the proper message to the IPC. On vehicles without a TCM, the IPC continually monitors the hard wired TRS multiplexed input. For further diagnosis of the gear selector indicator or the IPC circuitry that controls this function. Refer to DIAGNOSIS AND TESTING . For further diagnosis of the TRS on vehicles without a TCM, refer to the transmission range sensor service information in 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC for the appropriate transmission.