Jeepjeepster wrote:
tjkj2002 wrote:
The KJ's OEM 195 degree t-stat doesn't start opening till 195 degrees and does not fully open till 218 degrees.The temp gauge in the cluster will register halfway when the engine temp is between 178 degrees-228-degrees.
Whats the point of a gauge if its not going to move with a 30 degree change? Thats b/c its an idiot gauge for idiots that do not understand what it does. I want to know the exact temp of my engine, not a rough estimate.

Right from the FSM..............
Quote:
ENGINE TEMPERATURE
GAUGE
DESCRIPTION
An engine coolant temperature gauge is standard
equipment on all instrument clusters. The engine
coolant temperature gauge is located in the right
lower corner of the instrument cluster, to the right of
the speedometer. The engine coolant temperature
gauge consists of a movable gauge needle or pointer
controlled by the instrument cluster circuitry and a
fixed 90 degree scale on the cluster overlay that
reads left-to-right from “C” (or Cold) to “H” (or Hot)
for all engines. An International Control and Display
Symbol icon for “Engine Coolant Temperature” is
located on the cluster overlay, in the center of the
gauge directly above the hub of the gauge needle.
The engine coolant temperature gauge graphics are
dark blue and black against a beige field, except for a
single light blue graduation at the far left (Cold) end
of the gauge scale and a single red graduation at the
far right (Hot) 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 blue graphics
appear blue and the red graphics appear red. The
orange gauge needle is internally illuminated. Gauge
illumination is provided by replaceable incandescent
bulb and bulb holder units located on the instrument
cluster electronic circuit board. The engine coolant
temperature gauge is serviced as a unit with the
instrument cluster.
OPERATION
The engine coolant temperature gauge gives an
indication to the vehicle operator of the engine coolant
temperature. 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 Programmable Communications
Interface (PCI) data bus. The engine coolant temperature
gauge is an air core magnetic 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 the gauge needle position and provides the
following features:
† Engine Temperature Normal Message - Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is within
the normal operating range [up to about 124° C (255°
F) for gasoline engines, or about 110° C (230° F) for
diesel engines], the gauge needle is moved to the relative
temperature position of the gauge scale.
† Engine Temperature High Message - Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is high
[above about 127° C (260° F) for gasoline engines, or
112° C (233° F) for diesel engines], the gauge needle
is moved into the center of the red warning zone on
the gauge scale.
† Engine Temperature Critical Message -
Each time the cluster receives a message from the
PCM indicating the engine coolant temperature is
critical [above about 132° C (269° F) for gasoline
engines, or 115° C (239° F) for diesel engines], the
gauge needle is moved to the high end of the red
warning zone on the gauge scale.
† Actuator Test - Each time the cluster is put
through the actuator test, the gauge needle will be
swept to the gauge calibration points on the gauge
scale in sequence in order to confirm the functionality
of the gauge and the cluster control circuitry.
The PCM continually monitors the engine coolant
temperature sensor to determine the engine operating
temperature. The PCM then sends the proper
engine coolant temperature messages to the instrument
cluster. For further diagnosis of the engine coolant
temperature gauge or the instrument cluster
circuitry that controls the gauge, (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS
AND TESTING). If the instrument cluster moves the
engine coolant temperature gauge needle to indicate
a high or critical engine temperature, it may indicate
that the engine or the engine cooling system requires
service. For proper diagnosis of the engine coolant
temperature sensor, the PCM, the PCI data bus, or
the electronic message inputs to the instrument cluster
that control the engine coolant temperature
gauge, a DRBIIIt scan tool is required. Refer to the
appropriate diagnostic information.