AMBIENT TEMPERATURE
INDICATOR
DESCRIPTION
An ambient temperature indicator is optional
equipment on all instrument clusters. In vehicles so
equipped, the ambient temperature indication can be
toggled with the clock indication on the right side of
the multi-function indicator Liquid Crystal Display
(LCD) located near the lower edge of the instrument
cluster, directly below the speedometer. The ambient
temperature indication consists of a numeric value
with a “+” (plus) or “2” (minus) prefix, and the unit
of measure is identified with the characters “°C”
(Canadian vehicles only) or “°F” (United States vehi-
cles only) located directly above the temperature
indication. The indications of the ambient tempera-
ture indicator are not visible when the LCD is not
illuminated. When illuminated the indications
appear as dark characters and icons silhouetted
against an amber field. When the exterior lighting is
turned Off, the display is illuminated at maximum
brightness. When the exterior lighting is turned On
the display illumination level can be adjusted in con-
cert with the cluster general illumination lighting
using the “+” (plus) and “2” (minus) multi-function
indicator push buttons. The ambient temperature
indicator is serviced as a unit with the instrument
cluster.
OPERATION
The optional ambient temperature indicator gives
an indication to the vehicle operator of the outside
air temperature. This indicator is controlled by the
instrument cluster microprocessor based upon cluster
programming and a hard wired input received by the
cluster from the ambient temperature sensor. The
ambient temperature indicator is completely con-
trolled by the instrument cluster logic circuit, and
that logic will allow this indicator to operate when-
ever the multi-function indicator Liquid Crystal Dis-
play (LCD) is activated. Therefore, the ambient
temperature indicator remains functional regardless
of the ignition switch position.
The vehicle operator can choose to have the ambi-
ent temperature indicator displayed instead of the
clock information, but the clock and ambient temper-
ature indicator cannot be displayed at the same time.
The clock or ambient temperature indicator display
option is selected using the multi-function indicator
clock switch on the instrument cluster circuit board.
This switch is actuated manually by depressing the
clock switch push button that extends through the
lower edge of the cluster lens below the left end of
the multi-function indicator. Actuating this switch
momentarily will toggle the display between the
clock and ambient temperature indicator modes.
Actuating this switch twice within about one second
will cause the display to toggle, but then automati-
cally revert to the originally selected mode after
about twenty seconds.
The ambient temperature sensor located below the
front bumper is a Negative Temperature Coefficient
(NTC) thermistor. The internal resistance of the sen-
sor is reduced as the ambient temperature rises. The
instrument cluster continually monitors the resis-
tance through the sensor to determine the tempera-
ture value to be displayed. The current value is
displayed immediately after the LCD is activated.
The display value will remain static regardless of
decreases in the sensor resistance (temperature ris-
ing) below vehicle speeds of 10 to 15 kilometers-per-
hour (6 to 9 miles-per-hour). Decreases in the sensor
resistance above 15 kilometers-per-hour (9 miles-per-
hour) and increases the sensor resistance (tempera-
ture falling) regardless of vehicle speed are displayed
subject to a sixty second delay.
The ambient temperature sensor is connected to
the instrument cluster in series between the ambient
temperature sensor return and sense circuits. The
ambient temperature sensor and the return and
sense circuits to the instrument cluster can be diag-
nosed using conventional diagnostic tools and meth-
ods. For proper diagnosis of the instrument cluster
circuitry that controls the ambient temperature indi-
cator, a DRBIIIt scan tool is required. Refer to the
appropriate diagnostic information.
BRAKE/PARK BRAKE
INDICATOR
DESCRIPTION
A brake indicator is standard equipment on all
instrument clusters. The brake indicator is located
near the lower edge of the instrument cluster, to the
left of the multi-function indicator display. In vehi-
cles built for the United States market, the brake
indicator consists of stencil-like cutout of the word
“BRAKE” in the opaque layer of the instrument clus-
ter overlay. In vehicles built for the Canadian mar-
ket, the brake indicator consists of the International
Control and Display Symbol icon for “Brake Failure”
imprinted within a rectangular cutout in the opaque
layer of the instrument cluster overlay. In either
case, the dark outer layer of the overlay prevents the
indicator from being clearly visible when it is not
illuminated. A red Light Emitting Diode (LED)
behind the cutout in the opaque layer of the overlay
causes the “BRAKE” text to appear in red, or the
icon to appear silhouetted against a red field through
VA INSTRUMENT CLUSTER 8J - 11
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