broken temp guage?

so last year I tried to fix my temperature gauge on my 2002 tj when I turn the key on it jump straight up to 200  even when its cold when I turn the jeep off of it stays there for a second and then drops down to 0 I replace the temperature sending unit on the thermostat housing  that didn't work at all I took thr dash apart and looked at the wires behind the gauges there was an orange 1 that was cut when I reconnected it and tried again nothing changed is there anything else to try , or is there a way to see if Maby the guage itself is just broke and I'll have to get a new instrument panel?  

While im at it I been looking at used instrument panels just incase and I found some cheap ones that say for 97-2000 tj is there a real difference between those and the one in my 02 tj they look the same from the picture but I wana be sure so I don't waste the money  

first access the trouble codes.. by cycling the key On , off , ON, off, ON, off, ON  without starting the motor and the last position is on in under 10 seconds.. the odometer will change from mileage to trouble codes.. post them..

which engine do you have. the 4.0 or the 2.5..  probably won't make a difference..

i will have to dig into the service manual for some research into the temp gauge..

so i will be back sometime tonight..  the chrysler manual i looked at was almost 2,000 pages..

here is a sample that you should try.

ACTUATOR TEST

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE
THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM
CAPACITOR TO DISCHARGE BEFORE PERFORMING
FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG
DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.

The instrument cluster actuator test will put the
instrument cluster into its self-diagnostic mode. In
this mode the instrument cluster can perform a selfdiagnostic
test that will confirm that the instrument
cluster circuitry, the gauges, the PCI data bus message
controlled indicator lamps, and the chime tone
generator are capable of operating as designed. During
the actuator test the instrument cluster circuitry
will sound the chime tone generator, position each of
the gauge needles at various specified calibration
points, illuminate each of the segments in the Vacuum-
Fluorescent Display (VFD), and turn all of the
PCI data bus message-controlled indicators on and
off again.

Successful completion of the actuator test will confirm
that the instrument cluster is operational. However,
there may still be a problem with the PCI data
bus, the Powertrain Control Module (PCM), the Airbag
Control Module (ACM), the Sentry Key Immobilizer
Module (SKIM), or the inputs to one of these
electronic control modules. Use a DRBIIIt scan tool
to diagnose these components. Refer to the appropriate
diagnostic information.

If an individual gauge does not respond properly,
or does not respond at all during the actuator test,
the instrument cluster should be removed. However,
check that the screws securing the inoperative gauge
to the instrument cluster electronic circuit board are
properly tightened before considering instrument
cluster replacement. If the gauge mounting screws
check OK, replace the faulty instrument cluster.

(1) Begin the test with the ignition switch in the
Off position.

(2) Depress the odometer/trip odometer switch button.

(3) While still holding the odometer/trip odometer
switch button depressed, turn the ignition switch to
the On position, but do not start the engine.

(4) Release the odometer/trip odometer switch button.

(5) The instrument cluster will automatically
begin the actuator test sequence, as follows:

(a) The cluster will generate a single chime tone
to confirm the functionality of the chime tone generator
and the chime control circuitry.

(b) The cluster will scroll the number “8” across
the odometer/trip odometer VFD to confirm the
functionality of all VFD segments and their control
circuitry.

(c) The cluster will illuminate the decimal point
in the odometer/trip odometer VFD to confirm the
functionality of this VFD segment and its control
circuitry.

(d) The cluster will display the EMIC software
level in the odometer/trip odometer VFD (example:
“SOF 8.9”).

(e) The cluster will display the last six digits
(sequence number) of the Vehicle Identification
Number (VIN) in the odometer/trip odometer VFD.

(f) If any faults have been set by the cluster, the
cluster will display the fault information in the
odometer/trip odometer VFD. If no faults have
been set, the cluster will scroll “no FAULtS” across
the odometer/trip odometer VFD.

(g) The cluster will turn on, then off again each
of the following indicators, one at a time, in
sequence to confirm the functionality of the indicator
and the cluster control circuitry:
² High Beam
² Brake
² Seatbelt
² MIL
² Check Gauges
² Low Fuel
² Full Time
² Part Time
² SKIS
² Cruise
² Upshift

(h) The cluster will sweep the needles for each of
the following gauges, one at a time, to several calibration
points in sequence to confirm the functionality
of the gauge and the cluster control circuitry:
² Speedometer
² Fuel
² Temperature
² Tachometer
² Voltage
² Oil Pressure

(6) The actuator test is now completed. The instrument
cluster will automatically exit the self-diagnostic
mode and return to normal operation at the
completion of the test, if the ignition switch is turned
to the Off position during the test, or if a vehicle
speed message indicating that the vehicle is moving
is received from the PCM over the PCI data bus during
the test.

(7) Go back to Step 1 to repeat the test, if
required.  

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 lower
right quadrant of the instrument cluster, below the
oil pressure gauge. The engine coolant temperature
gauge consists of a movable gauge needle or pointer
controlled by the instrument cluster electronic circuitry
and a fixed 90 degree scale on the cluster overlay
that reads left-to-right from 40° C (or 100° F) to
125° C (or 260° *** 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
white and blue against a black field except for a single
red graduation 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
white graphics appear white, 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 electronic circuit board based
upon the 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:

² Engine Temperature Message - Each time
the cluster receives a message from the PCM indicating
the engine coolant temperature is between about
40° C (100° F) and 124° C (255° *** the gauge needle
is moved to the appropriate linear position on the
gauge scale to represent the actual engine temperature.
The gauge needle will continue to be positioned
at the actual temperature position on the gauge scale
until the cluster receives a message from the PCM
that indicates the engine temperature is low, high, or
critical, or until the ignition switch is turned to the
Off position, whichever occurs first.
²

Engine Temperature Low Message - Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is at or
below about 40° C (100° *** the gauge needle is held
at the 40° C (100° F) graduation at the far left end of
the gauge scale. The gauge needle remains at the far
left end of the scale until the cluster receives a message
from the PCM indicating that the engine temperature
is above about 40° C (100° *** or until the
ignition switch is turned to the Off position, whichever
occurs first.
²

Engine Temperature High Message - Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is about
127° C or higher (about 261° F or higher), the gauge
needle is moved to the center of the red zone on the
gauge scale, the check gauges indicator is illuminated,
and a single chime tone is sounded. The chime
tone feature will occur only once per ignition cycle.
The gauge needle remains in the center of the red
zone and the check gauges indicator remains illuminated
until the cluster receives a message from the
PCM indicating that the engine temperature is about
124° C or lower (about 255° F or lower), or until the
ignition switch is turned to the Off position, whichever
occurs first.
²
Engine Temperature Critical Message -
Each time the cluster receives a message from the
PCM indicating the engine coolant temperature is
about 129° C or higher (about 264° F or higher), the
gauge needle is moved to the far right end of the red
zone on the gauge scale. The gauge needle remains
at the far right end of the red zone until the cluster
receives a message from the PCM indicating that the
engine temperature is about 127° C or lower (about
261° F or lower), or until the ignition switch is
turned to the Off position, whichever occurs first.
² Message Failure - If the cluster fails to receive
an engine temperature message for more than about
twelve seconds, it will move the gauge needle to the
minimum graduation of the gauge scale until a new
message is received, or until the ignition switch is
turned to the Off position, whichever occurs first.
² Actuator Test - Each time the cluster is put
through the actuator test, the gauge needle will be
swept to several calibration points on the gauge scale
in a prescribed sequence 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 turns on
the check gauges indicator due to a high or critical
engine temperature gauge reading, 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 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.  

It's a 4.0 and the codes I got were P 0138 and P0455  

P0138  1/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal operating range.

P0455  Evap Leak Monitor Large Leak Detected.  A large leak has been detected in the evaporative system.



time to plug in an OBD2 scan tool...  look at the oxygen sensor voltage..  many scan tools can graph the voltage signal.

see if you get nice full swings when the engine is held at a steady 2500 RPMs..   steady foot instead of trying to maintain the rpms..  as you want to see the sensor voltage swinging instead of the reaction to the throttle movement..

you are also going to want to do a voltage drop test  with a digital volt meter as a BAD engine ground can cause the oxygen sensor to do crazy thing.. a bad sensor heater ground can also do this..  this takes 2 minutes ..

with a digital volt meter set to 20 volts DC scale..   engine running.. headlights on..

1.   test between the Negative battery post and the positive battery post..  14.1 to 14.8 volts is expected

2.  test between the Negative battery post and the engine block..  0.04 volts is expected

3. test between the Negative battery post and the body...  0.02 volts is expected..

4. test between the ENGINE and the BODY.. 0.02 volts is expected.

if you get 0.00 volts.. change the meter setting to 2 volts scale..   retest 2, 3, 4.

you are actually measuring the connection between the parts with the voltage flowing through..  if you get more than the 0.04 or 0.02 you have a bad ground connection .. if you get 0.00.. you have an invalid test ..  

this cures a LOT of problems in cars by this two minute test..

p0455 is harder.. as it usually requires a more advanced scan tool to look at the fuel tank pressures and operate the solenoid valves and vacuum testing pump on some models..   could also be as simple as leaving the gas tank cap loose.. or filling with the engine running..

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
about the temp gauge..
while you have the OBD2 scan tool plugged in.. i would like you to look at the engine coolant temp while looking at the live data stream...

P0116 Coolant Temp Sensor Performance A rationatilty error has been detected in the coolant temp
sensor.

P0117 (M) ECT Sensor Voltage Too Low Engine coolant temperature sensor input below the
minimum acceptable voltage.

P0118 (M) ECT Sensor Voltage Too High Engine coolant temperature sensor input above the
maximum acceptable voltage.

if you disconnect the engine coolant sensor you should see the coolant temp drop to -20F..
if you jump the disconnected pigtail.. the temp should show 299F..  on the scan tool..

this shows the wiring is intact..     the engine coolant temp sensor is what the PCM uses for engine fuel calculations. but also shares it with the instrument cluster via the data buss called CAN..  

I don't think you could have explained it all any better I did the actuater test and it all seemed to work in the begining I saw something say bus 68 does that mean anything? Also all the fishes went threw and worked except the temp  

buS b0 PCM - MIL Message The cluster is not receiving a MIL lamp
message from the PCM. A DRBIIIT scan tool
is required for further diagnosis. Refer to the
appropriate diagnostic information.

buS b1 SKIM - SKIM Message The cluster is not receiving a SKIS lamp
message from the SKIM. A DRBIIIT scan tool
is required for further diagnosis. Refer to the
appropriate diagnostic information.

buS b8 ACM - Airbag Message The cluster is not receiving an Airbag lamp
message from the ACM. A DRBIIIT scan tool
is required for further diagnosis. Refer to the
appropriate diagnostic information.

PanEL OPEn Panel Sense - Open Circuit The cluster is not receiving an input from the
the panel lamps dimmer circuitry of the left
multi-function switch on the panel lamps
dimmer signal circuit. Repair the open circuit
or replace the faulty switch as required.
Airbag Telltale Open/Shorted The EMIC airbag indicator is open or shorted.
Replace the faulty cluster.


check your messages above left when logged in...  

The b8 message makes some.sence my airbad isn't connect the person before me for somereason cut the wires to it and messed up numerious other wires, that panel open thing did POP up during the scan also thanks for the link  

when you mentioned cut wires.. i thought you were going to need that..

i hope you have a tablet of some kind to carry it around with..

ask questions if you need more help...

harbor freight sells logic probes for cheep...

Computer Safe Automotive Logic Probe Item #98709