Transmission Range Indicator

The gear selector indicator is serviced as a unit with the odometer vacuum fluorescent display unit in the instrument cluster.

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 cluster circuit board based upon cluster programming and electronic messages received from the transmission control module over the controller area network data bus.

The gear selector indicator information is displayed by the odometer VFD unit soldered onto the instrument cluster electronic circuit board, and the VFD will not display the gear selector indicator information after the ignition switch is turned to the OFF position. Each time the cluster is disconnected from battery current for more than about 5 minutes, it must configure itself for the automatic transmission type that is in the vehicle once it is reconnected to battery current. The instrument cluster circuitry operates the gear selector indicator to provide the following features:

• >>Selected Gear Message<< - Each time the cluster receives an electronic selected gear message from the TCM, a box will be illuminated around the appropriate character in the gear selector indicator. The box will remain illuminated until the cluster receives a different selected gear message, or until the ignition switch is turned to the OFF position, whichever occurs first.
• >>Communication Error<< - If the cluster fails to receive a selected gear message from the PCM within 3 seconds, the instrument cluster circuitry will display all gear selector positions boxed (selected) until a valid selected gear message is received or until the ignition switch is turned to the OFF position, whichever occurs first.
• >>Actuator Test<< - Each time the cluster is put through the actuator test, the odometer VFD unit will display all of its characters at once to confirm the functionality of the VFD unit and the cluster control circuitry.

The TCM continually monitors a hard wired multiplex input from the transmission range sensor, then sends the proper message to the electromechanical instrument cluster.

A diagnostic scan tool is required for proper diagnosis of the TRS, the TCM, the EMIC, the CAN data bus or the electronic communication related to gear selector indicator operation. Refer to the appropriate diagnostic information.