Fig. 35: Tachometer
Courtesy of CHRYSLER LLC
A tachometer is standard equipment on all instrument clusters. The tachometer is located to the right of the
speedometer in the instrument cluster. The tachometer consists of a movable gauge needle or pointer controlled
by the instrument cluster circuitry and a fixed 185 degree scale on the gauge dial face that reads left-to-right
either from 0 to 7 for vehicles with a gasoline engine, or from 0 to 6 for vehicles with a diesel engine. The text
RPM X 1000 imprinted on the cluster overlay directly above the hub of the tachometer needle identifies that
each number on the tachometer scale is to be multiplied by 1000 RPM.
The tachometer graphics are white, gray and black against a black field except for several red graduations that
designate the red line area at the high end of the gauge scale, 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 graphics retain their unilluminated colors and appearance. The
orange gauge needle has internal optical illumination. Gauge illumination 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.
OPERATION
TACHOMETER
The tachometer gives an indication to the vehicle operator of the engine speed. This gauge is controlled by the
instrument cluster circuit board based upon cluster programming and electronic messages received by the
cluster from the Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus.
The tachometer is driven by an electronic stepper motor unit that receives battery current on the instrument
cluster electronic circuit board through the fused ignition switch output (run-start) circuit whenever the ignition
switch is in the ON or START positions. 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
2007 Dodge Nitro R/T
2007 ACCESSORIES AND EQUIPMENT Instrument Cluster - Service Information - Nitro