Dodge Nitro. Manual — part 813

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

the gauge needle position and provides the following features:



Engine Speed Message - Each time the cluster receives an electronic engine speed message from the
PCM it will calculate the correct engine speed reading and position the gauge needle at that relative speed
position on the gauge scale. The cluster will receive a new message and reposition the gauge pointer
accordingly about every 88 milliseconds. The gauge needle will continually be repositioned at the relative
engine speed position on the gauge scale until the engine stops running, or until the ignition switch is
turned to the OFF position, whichever occurs first.



Communication Error - If the cluster fails to receive a speed 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.



Actuator Test - Each time the cluster is put through the actuator test, the tachometer needle will be swept
to several calibration points on the gauge scale in a prescribed sequence in order to confirm the
functionality of the gauge and the cluster control circuitry.

The PCM continually monitors the crankshaft position sensor to determine the engine speed. The PCM then
sends the proper engine speed messages to the Electro Mechanical Instrument Cluster (EMIC) (also known as
the Cab Compartment Node/CCN).

For proper diagnosis of the crankshaft position sensor, the PCM, the EMIC, the CAN data bus or the electronic
communication related to tachometer operation a diagnostic scan tool is required. Refer to the appropriate
diagnostic information.

TOW/HAUL INDICATOR

DESCRIPTION

TOW/HAUL INDICATOR

Fig. 36: Identifying Tow/Haul Indicator
Courtesy of CHRYSLER LLC

A tow/haul indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with
an optional automatic transmission this indicator is electronically disabled. This indicator is located near the
base of the speedometer needle hub on the cluster overlay, just right of center.

2007 Dodge Nitro R/T

2007 ACCESSORIES AND EQUIPMENT Instrument Cluster - Service Information - Nitro

The tow/haul indicator consists of a stencil-like cutout of the text TOW/HAUL 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. An amber Light Emitting Diode (LED) behind the cutout in the opaque layer of the
overlay causes the indicator to appear in amber through the translucent outer layer of the overlay when it is
illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board.

The tow/haul indicator is serviced as a unit with the instrument cluster.

OPERATION

TOW/HAUL INDICATOR

The tow/haul indicator gives an indication to the vehicle operator when the tow/haul function of the tow/haul
switch has been selected, revising the shift schedule of the electronically controlled automatic transmission.
This indicator is controlled by a transistor on 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 tow/haul indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic
circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery
current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be OFF
when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided
a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the tow/haul indicator
for the following reasons:



Tow/Haul Indicator Lamp-On Message - Each time the cluster receives an electronic tow/haul
indicator lamp-ON message from the PCM indicating that the tow/haul shift schedule has been selected,
the indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF
message from the PCM, 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 tow/haul indicator will be
turned ON, then OFF again during the bulb check portion of the test to confirm the functionality of the
LED and the cluster control circuitry.

The PCM continually monitors the tow/haul switch to determine the proper outputs to the automatic
transmission. The PCM then sends the proper lamp-ON or lamp-OFF message to the Electro Mechanical
Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN). For further diagnosis of the
tow/haul indicator or the instrument cluster circuitry that controls the LED, see DIAGNOSIS AND TESTING.

For proper diagnosis of the transmission control system, the PCM, the EMIC, the CAN data bus or the
electronic communication related to tow/haul indicator operation a diagnostic scan tool is required. Refer to the
appropriate diagnostic information.

TIRE PRESSURE MONITOR INDICATOR

DESCRIPTION

TIRE PRESSURE MONITOR INDICATOR

2007 Dodge Nitro R/T

2007 ACCESSORIES AND EQUIPMENT Instrument Cluster - Service Information - Nitro

Fig. 37: Tire Pressure Monitor Indicator
Courtesy of CHRYSLER LLC

A Tire Pressure Monitor (TPM) indicator is standard equipment on all instrument clusters. However, on
vehicles not equipped with the TPM system, this indicator is electronically disabled. This indicator is located
within the odometer Vacuum Fluorescent Display (VFD) unit.

The TPM indicator consists of a stencil-like cutout of an icon that represents a cross-section of a tire with a
centered exclamation point in the VFD unit. The odometer VFD unit is soldered onto the instrument cluster
electronic circuit board, and is visible through a window with a smoked clear lens located on the lower edge of
the tachometer gauge dial face of the cluster overlay. The dark lens over the VFD prevents it from being clearly
visible when it is not illuminated. The indicator appears in an amber color when it is illuminated by the cluster
electronic circuit board, and the TPM indicator as well as all of the odometer VFD information is illuminated at
full (daytime) brightness and cannot be dimmed until the TPM indicator is extinguished.

The TPM indicator is serviced as a unit with the odometer VFD unit in the instrument cluster.

OPERATION

TIRE PRESSURE MONITOR INDICATOR

The Tire Pressure Monitor (TPM) indicator gives an indication to the vehicle operator of the status of the TPM
system. The TPM indicator is controlled by the instrument cluster circuit board based upon cluster
programming and electronic messages received by the cluster from the Sentry Key REmote Entry Module
(SKREEM) (also known as the Wireless Control Module/WCM) over the Controller Area Network (CAN) data
bus.

The TPM indicator is completely controlled by the instrument cluster logic circuit, and that logic will only
allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition
switch output (run-start) circuit. Therefore, the indicator will always be OFF when the ignition switch is in any
position except ON or START. The indicator only illuminates when it is energized by the instrument cluster

2007 Dodge Nitro R/T

2007 ACCESSORIES AND EQUIPMENT Instrument Cluster - Service Information - Nitro