The instrument cluster continually monitors the
status of the driver side front seat belt switch and
the airbag indicator circuit to determine the proper
seatbelt indicator response. The seat belt switch is
connected in series between the instrument cluster
and ground. The seat belt switch and the seatbelt
indicator driver circuit to the instrument cluster can
be diagnosed using conventional diagnostic tools and
methods. For proper diagnosis of the ACM, the air-
bag (SRS) indicator, or the instrument cluster cir-
cuitry that controls the seatbelt indicator, a DRBIIIt
scan tool is required. Refer to the appropriate diag-
nostic information.
SPEEDOMETER
DESCRIPTION
A speedometer is standard equipment on all instru-
ment clusters. The speedometer is located in the cen-
ter of the instrument cluster. The speedometer
consists of a movable gauge needle or pointer con-
trolled by the instrument cluster circuitry and a fixed
210 degree primary outer scale on the gauge dial face
that reads left-to-right either from “0” to “100” miles-
per-hour, or from “0” to “180” kilometers-per-hour,
depending upon the market for which the vehicle is
manufactured. Each version also has a secondary
inner scale on the gauge dial face that provides the
equivalent opposite units from the primary scale.
Text appearing on the cluster overlay near the left
end of each scale abbreviates the unit of measure,
either “mph” or “km/h”.
The speedometer graphics are white against a
black field, making them clearly visible within the
instrument cluster in daylight. When illuminated
from behind by the panel lamps dimmer controlled
cluster illumination lighting with the exterior lamps
turned On, the white graphics appear amber. The
orange gauge needle is internally illuminated. Gauge
illumination is provided by Light Emitting Diode
(LED) units soldered onto the instrument cluster
electronic circuit board. The speedometer is serviced
as a unit with the instrument cluster.
OPERATION
The speedometer gives an indication to the vehicle
operator of the vehicle road speed. This gauge is con-
trolled by the instrument cluster circuit board based
upon cluster programming and electronic messages
received by the cluster from the Controller Anti-lock
Brake (CAB) over the Controller Area Network
(CAN) data bus. The speedometer is an air core mag-
netic unit that receives battery current on the instru-
ment cluster electronic circuit board when the
instrument cluster detects that the ignition switch is
in the On position. The cluster is programmed to
move the gauge needle back to the low end of the
scale after the ignition switch is turned to the Off
position. The instrument cluster circuitry controls
the gauge needle position and provides the following
features:
• Vehicle Speed Message - Each time the clus-
ter receives a vehicle speed message from the CAB it
will calculate the correct vehicle speed reading and
position the gauge needle at that relative speed posi-
tion on the gauge scale. The gauge needle will con-
tinue to be positioned at the actual vehicle speed
position on the gauge scale until the ignition switch
is turned to the Off position.
• Communication Error -
If the cluster fails to
receive a speedometer message, it will hold the gauge
needle at the last indication for about three seconds, or
until the ignition switch is turned to the Off position,
whichever occurs first. After three seconds, the gauge
needle will return to the left end of the gauge scale.
The CAB continually monitors the four wheel
speed sensors to determine the vehicle road speed.
The CAB then sends the proper vehicle speed mes-
sages to the instrument cluster. For proper diagnosis
of the wheel speed sensors, the CAB, the CAN data
bus, or the electronic message inputs to the instru-
ment cluster that control the speedometer, a DRBIIIt
scan tool is required. Refer to the appropriate diag-
nostic information.
TACHOMETER
DESCRIPTION
A tachometer is standard equipment on all instru-
ment clusters. The tachometer is located to the left of
the speedometer, to the left of center in the instru-
ment cluster. The tachometer consists of a movable
gauge needle or pointer controlled by the instrument
cluster circuitry and a fixed 45 degree scale on the
gauge dial face that reads left-to-right from “0” to “7”.
The text “rpm X 1000” imprinted on the cluster over-
lay near the left end of the gauge scale identifies that
each number on the tachometer scale is to be multi-
plied by 1000 rpm.
The tachometer graphics are white against a black
field, making them clearly visible within the instru-
ment cluster in daylight. When illuminated from
behind by the panel lamps dimmer controlled cluster
illumination lighting with the exterior lamps turned
On, the white graphics appear amber. The orange
gauge needle is internally illuminated. Gauge illumi-
nation is provided by Light Emitting Diode (LED)
units soldered onto the instrument cluster electronic
circuit board. The tachometer is serviced as a unit
with the instrument cluster.
VA INSTRUMENT CLUSTER 8J - 23
SEATBELT INDICATOR (Continued)
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