Grand Cherokee 4WD V8-4.7L Flex Fuel (2009)
Speedometer Head: Description and Operation
Speedometer - Description
DESCRIPTION
A speedometer is standard equipment on all instrument clusters. The speedometer is located to the left of center in the instrument cluster, between the
tachometer and the fuel gauge. The speedometer consists of a movable gauge needle or pointer controlled by the instrument cluster circuitry and a fixed
210 degree primary scale on the gauge dial face. For all vehicles except SRT8 the speedometer reads left-to-right either from 0 to 140 mph, or from 0 to
230 km/h, depending upon the market for which the vehicle is manufactured. On SRT8 the speedometer reads left-to-right either from 0 to 180 mph, or
from 0 to 300 km/h, 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.
On all vehicles except SRT8, text appearing on the cluster overlay above the hub of the speedometer needle abbreviates the unit of measure for the
primary scale (either MPH or km/h), and text inside the low end of the secondary scale indicates the unit of measure for that scale. On SRT8 the text
identifying the unit of measure for the primary scale is located below the left end of the scale, and the text identifying the unit of measure for the
secondary scale is located below the right end of the scale.
On all vehicles the speedometer graphics are gray and white against a black field. In all Laredo vehicles, the gauge graphics are 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 text and graphics still appear white and the gray graphics still appear gray. The red gauge needle has internal optical illumination.
Gauge illumination is provided by Light Emitting Diode (LED) units soldered onto the instrument cluster electronic circuit board.
In all vehicles except Laredo, the gauge graphics are nearly invisible within the instrument cluster in daylight while the ignition switch is in the OFF
position. When the ignition is turned ON the gauge is illuminated from behind at full brightness by the cluster illumination lighting. The white text and
graphics still appear white and the gray graphics still appear gray. The white gauge needle has internal optical illumination. With the exterior lamps
turned ON, the cluster illumination lighting is panel lamps dimmer controlled. Gauge illumination is provided by LED units soldered onto the instrument
cluster electronic circuit board.
The speedometer is serviced as a unit with the instrument cluster.
