Commander 4WD V8-4.7L VIN N (2006)
Transmission Mode Indicator - A/T: Description and Operation
GEAR SELECTOR INDICATOR
DESCRIPTION
An electronic automatic transmission gear selector indicator is standard factory-installed equipment on this model. However, on vehicles not equipped
with an optional automatic transmission, this indicator is electronically disabled. This indicator is located within the fixed segment Organic Light
Emitting Diode (OLED) display unit. The gear selector indicator information is displayed in the upper left corner of the OLED display.
The fixed segment OLED display unit is soldered onto the cluster electronic circuit board, and is visible through a window with a smoked clear lens
located on the lower edge of the speedometer gauge dial face of the cluster overlay. The dark lens over the OLED prevents it from being clearly visible
when it is not illuminated. The gear selector indicator within the fixed segment OLED consists of the characters from left to right: P, R, N and a fourth,
reconfigurable character. Each character appears in a blue-green color and at the same lighting level as the odometer information.
Respectively, the indicator characters represent PARK, REVERSE, NEUTRAL and the various forward drive gear positions of the transmission gear
selector lever on the floor panel transmission tunnel. The OLED changes the reconfigurable character to a letter D or the numbers 1 through 4 to
represent the currently selected forward gear and illuminates brackets [ ] on each side of the appropriate character to indicate the current selection.
During daylight hours (exterior lamps are OFF) the fixed segment OLED is illuminated at full brightness for clear visibility. At night (exterior lamps are
ON), the OLED lighting level is adjusted with the other cluster illumination lamps using the panel lamps dimmer function of the interior lighting control
sleeve on the left multi-function switch control stalk. However, a Parade mode position of the control sleeve allows the OLED to be illuminated at full
brightness if the exterior lamps are turned ON during daylight hours.
The gear selector indicator is serviced as a unit with the fixed segment OLED display unit in the instrument cluster.
OPERATION
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 logic circuit based upon cluster programming and electronic
messages received from the Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus.
The gear selector indicator information is displayed by the fixed segment Organic Light Emitting Diode (OLED) display unit soldered onto the
instrument cluster electronic circuit board, and the OLED 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 five minutes, it must configure itself for the automatic
transmission model 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:
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Selected Gear Message - Each time the cluster receives a selected gear message from the PCM, brackets [ ] will be illuminated around the
appropriate character in the gear selector indicator. The brackets 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.
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Communication Error - If the cluster fails to receive a selected gear message from the PCM within three seconds, the instrument cluster
circuitry will display all gear selector positions bracketed (selected) until a valid selected gear message is received or until the ignition switch is
turned to the OFF position, whichever occurs first.
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Actuator Test - Each time the cluster is put through the actuator test, the odometer fixed segment OLED will display all of its characters at once
to confirm the functionality of the OLED and the cluster control circuitry.
The PCM continually monitors a hard wired multiplex input from the Transmission Range Sensor (TRS), then sends the proper selected gear messages to
the instrument cluster. For proper diagnosis of the TRS, the PCM, the CAN data bus, or the electronic message inputs to the instrument cluster that
control the gear selector indicator, a diagnostic scan tool is required.
