Dakota Quad Cab 4WD V6-3.9L VIN X (2001)
Transmission Shift Position Indicator Lamp: Description and Operation
GEAR SELECTOR INDICATOR
An electronic automatic transmission gear selector indicator is standard factory-installed equipment on this model. The gear selector indicator
information is displayed in a Vacuum-Fluorescent Display (VFD), which is visible through a small window cutout located in the lower right
quadrant of the cluster overlay. The gear selector indicator displays the following characters from left to right: 'P," "R," "N," "D," "2," and "1."
Respectively, these characters represent the park, reverse, neutral, drive, second gear, and first gear positions of the transmission gear selector
lever on the steering column. The VFD illuminates a rectangular box around the character that represents the currently selected lever position.
During daylight hours (exterior lamps OFF) the gear selector indicator VFD is illuminated at full brightness for clear visibility. At night (exterior
lamps are ON) the VFD lighting level is adjusted with the other cluster illumination lamps using the panel lamps dimmer thumbwheel on the
headlamp switch. However, a "Parade" mode position of the panel lamps dimmer thumbwheel allows the VFD to be illuminated at full brightness
while the exterior lamps are turned ON during daylight hours. The gear selector indicator VFD is serviced as a unit with 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 gauge is controlled by the instrument cluster circuit board based upon cluster programming. The cluster
circuitry automatically configures itself for the proper automatic transmission model based upon the hard wired transmission range sensor mux
circuit input to the cluster. Each time the cluster is disconnected from battery current for more than about five minutes, it must configure itself
again for the automatic transmission model that is in the vehicle when it is reconnected to battery current. The gear selector indicator information
is displayed by a dedicated Vacuum Fluorescent Display (VFD) on 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. The instrument cluster circuitry configures the gear
selector indicator VFD based upon the following inputs from the transmission range sensor:
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Open Circuit - If the transmission range sensor mux circuit is open, the cluster circuitry controls the gear selector indicator display based
upon electronic messages received from the electronic Transmission Control Module (TCM) over the Programmable Communications
Interface (PCI) data bus. If the input is open circuit and no electronic messages are received from the TCM within two seconds, the instrument
cluster circuitry will cycle the indicated gear selector position from P to R, to N, to D to 2 repeatedly and continuously until the condition is
resolved or until the ignition switch is turned to the OFF position, whichever occurs first.
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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 transmission range sensor. If the cluster has configured itself for the
transmission range sensor input and detects a short to ground in the transmission range sensor mux input, the cluster will indicate all positions
in the VFD; or, if this input is open circuit, the cluster will blink all positions in the VFD. The VFD display for the short-to-ground and open
circuit conditions will continue until the condition is resolved 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 VFD will display all of its characters at once, then step through each
character segment individually during the VFD portion of the test to confirm the functionality of the VFD and the cluster control circuitry.
On models with a TCM, the TCM continually monitors the transmission range sensor, then sends the proper gear selector indicator messages to the
instrument cluster. On models without a TCM, the instrument cluster continually monitors the hard wired transmission range sensor multiplexed
input. For further diagnosis of the gear selector indicator or the instrument cluster circuitry that controls this function, (Refer to INSTRUMENT
CLUSTER - DIAGNOSIS AND TESTING). On models with a TCM, for proper diagnosis of the transmission range sensor, the TCM, the PCI
data bus, or the message inputs to the instrument cluster that control the gear selector indicator, a DRB III scan tool is required. Refer to the
appropriate diagnostic information.
