transmission and automatic transmission model based upon the hard wired transmission range sensor mux circuit
input to the cluster.
The gear selector indicator information is displayed by a dedicated Vacuum Fluorescent Display (VFD) unit soldered
onto the instrument cluster electronic circuit board, and the VFD will not display the gear selector indicator infor-
mation 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 configures the gear selector indi-
cator VFD based upon the following inputs from the transmission range sensor:
•
Open Circuit - If the cluster is configured for an automatic transmission and the transmission range sensor
mux circuit is open, the cluster circuitry controls the gear selector indicator display based upon electronic mes-
sages received from the electronic Transmission Control Module (TCM) over the Programmable Communica-
tions Interface (PCI) data bus. If the transmission range sensor mux circuit is open and no electronic
messages are received from the TCM within two seconds, the instrument cluster 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 transmission
range sensor. If the cluster is configured for an automatic transmission with a transmission range sensor input
and detects a short to ground or an open in the transmission range sensor mux input, the instrument cluster
circuitry will not display any gear selector position 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.
•
Actuator Test - Each time the cluster is put through the actuator test, the gear selector indicator VFD will
display all of its characters at once 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 position 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 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - DIAGNOSIS AND TESTING). For further diagnosis of the transmission range sensor on models
without a TCM, (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RE/TRANSMISSION RANGE SEN-
SOR - DIAGNOSIS AND TESTING) or (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 46RE/TRANS-
MISSION RANGE SENSOR - DIAGNOSIS AND TESTING).
On models with a TCM, for proper diagnosis of the transmission range sensor, the TCM, the PCI data bus, or the
electronic message inputs to the instrument cluster that control the gear selector indicator, a diagnostic scan tool is
required. Refer to the appropriate diagnostic information.
HIGH BEAM INDICATOR
DESCRIPTION
A high beam indicator is standard equipment on all
instrument clusters. This indicator is located near the
upper edge of the instrument cluster, between the
tachometer and the speedometer.
The high beam indicator consists of a stencil-like cutout of the International Control and Display Symbol icon for
“High Beam” in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the
indicator from being clearly visible when it is not illuminated. A blue Light Emitting Diode (LED) behind the cutout in
the opaque layer of the overlay causes the icon to appear in blue through the translucent outer layer of the overlay
when the indicator is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic
circuit board. The high beam indicator is serviced as a unit with the instrument cluster.
OPERATION
The high beam indicator gives an indication to the vehicle operator whenever the headlamp high beams are illumi-
nated. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster pro-
8J - 128
INSTRUMENT CLUSTER -SERVICE INFORMATION
DR/DH