another dead battery

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twindragons187

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i went out to start my kj the other morning, and click.....all lights out in the dash, rear gate is clicking.....ok, try jump start.....it wont start...hmmm...ok
try starting with foot on pedal....works!!...then dies...??....ok, i'm gettting pissed.....try again, this time have father in-law disconnect jumper cables after it starts.....ok, dash lights go nuts.....then all dash lights and all needles go dead...But....jeep still running(still have foot on gas)???? let off gas, jeep dies....ok, i have the extended warrantee, try to call them on a sunday....yea right.....ok, get on here and start searching, find kj won't start...start reading......interesting......just a battery?? God i hope so....find out on payday.
 

JeepJeepster

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Keep your foot in the gas till it will idle.

I would recommend trying to charge the battery before jumping it anymore. If it wont take charge then get a new battery and go on your way. :)
 

twindragons187

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yea i figured that. still the orig. battery from jan 03. them little indicators lie...mines still green....
 

VTNomad

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Alternator

My money is on the battery. It's old enough to just goahead and replace. However, if the problem happens again you may want to have your alternator (which charges the battery) checked. Advanced Auto, or Autozone usually check your alternator for free.
 

tjkj2002

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My money is on the battery. It's old enough to just goahead and replace. However, if the problem happens again you may want to have your alternator (which charges the battery) checked. Advanced Auto, or Autozone usually check your alternator for free.
Checking the alternator on a KJ(and many newer vehicles) they way autozone does will always give you a false reading of how the alternator is actually preforming since the PCM controls the alternator.The alternator will only produce what the PCM wants it to(up to the max amps that the alt is rated for).Places like autozone only can test the old style alternators that are not controlled by the PCM,even though they will still test it for(since they are all idiots anyway).You will need a couple thousand dollars worth of specialized tools(some that you can not get) to properly test our alternators.
 

JeepJeepster

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How does the thousands of dollars worth of tools check it?? I always figured they just put a load on the alternator and if it takes the load then its good.

If the voltage drops then its bad...
 

tjkj2002

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How does the thousands of dollars worth of tools check it?? I always figured they just put a load on the alternator and if it takes the load then its good.

If the voltage drops then its bad...
Well you need to override the PCM sensors that control alternator.Just because you place a load on the system does not mean the alternator will increase it's voltage and amp output(most times it will but not always),there are many factors before that will happen.So yes there will be a great number of times that your electrical system is running off of battery power also since there are conditions that would damage both the battery and/or the alternator.
 

sstcobra1

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Same thing happened to me yesterday morning. Went to start 2004 Jeep and it would not turn over. Using a portable "jumper" battery, limped to the dealership. New battery and I'm on my way! Less $159.00 of course!
 

JeepJeepster

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I got a new battery for $80 and put it in myself. Got it at Advance. Its a 800CCA and 1000CA.

A red top optima is $150. Did you get the stock mopar battery sstcobra? :confused:
 

twindragons187

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it was the battery. had it tested and was only reading .3 volts in 3 cells. but the battery tester thats on it still read green..... was wierd... thanks for all the help.
 

Mangate

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The OEM batteries on both my Libbys are black on the indicator and both are working fine, I'm just expecting then to die at any moment, but who knows.
 

Dave

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Speaking of batteries......a buddy called me earlier today and I had to go and get him and his pos 4 year old mopar jeep battery and exchange it. He was stranded near wallyworld so he got their 875cca/1,000ca yellow maxx battery for $79. We'll see how it lasts.

Mine is probably next.

Dave
 
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moparman

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The "battery tester" in the battery is only in one cell, there are 5 more that will fail. It is more of a general charge indicator. It is just showing that the one cell is charged.
 

Dave

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The "battery tester" in the battery is only in one cell, there are 5 more that will fail. It is more of a general charge indicator. It is just showing that the one cell is charged.

100% true. Because in the old days you would just pop the caps off and test each cell seperately. You could even top them off. Not today when you need a chainsaw to open a "new fangled modern" sealed battery.

Dave

P S - Dear Jeep Gods......Please give me back my old fashioned battery and Warn manual locking hubs.......I promise I will be good.....:D
 

JeepJeepster

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I often check the water in most of the batteries we have. More so in a boat but its not even possible to check it in an optima.
 

bmj2008

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or you can take the alternator off and properly check the alternator at autozone. oh and people that work at autozone are not idiots. maybe where you come from but do not make a general asumption about all employees tjkj2002. if its not apparent i work there
 

tjkj2002

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or you can take the alternator off and properly check the alternator at autozone. oh and people that work at autozone are not idiots. maybe where you come from but do not make a general asumption about all employees tjkj2002. if its not apparent i work there
Okay 99% of them are:D.

Oh and even taking the KJ alternator off and taking it to autozone to have tested will not work since the voltage regulator is still in the PCM.The KJ's alternator is not a stand alone tpue of alternator and needs inputs from the PCM to function and even test.

Autozone can test alternators from a '90's Ford pickup or '90's chevy car that has the built in voltage regulator.

From the FSM

VOLTAGE REGULATOR​
DESCRIPTION​
The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulating
circuit located within the Powertrain Control
Module (PCM). The EVR is not serviced separately. If​
replacement is necessary, the PCM must be replaced.

OPERATION​
The amount of DC current produced by the generator
is controlled by EVR circuitry contained within
the Powertrain Control Module (PCM). This circuitry
is connected in series with the generators second
rotor field terminal and its ground.
Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. The
EVR circuitry monitors system line voltage (B+) and
battery temperature (refer to Battery Temperature
Sensor for more information). It then determines a
target charging voltage. If sensed battery voltage is
0.5 volts or lower than the target voltage, the PCM
grounds the field winding until sensed battery voltage
is 0.5 volts above target voltage. A circuit in the
PCM cycles the ground side of the generator field up
to 100 times per second (100Hz), but has the capability
to ground the field control wire 100% of the time
(full field) to achieve the target voltage. If the charging
rate cannot be monitored (limp-in), a duty cycle
of 25% is used by the PCM in order to have some
generator output. Also refer to Charging Operation​
for additional information

CHARGING SYSTEM​
DESCRIPTION​
The charging system consists of:​
†​
Generator

†​
Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM)

†​
Ignition switch

†​
Battery (refer to 8, Battery for information)

†​
Battery temperature sensor

†​
Generator Lamp (if equipped)

†​
Check Gauges Lamp (if equipped)

†​
Wiring harness and connections (refer to 8, Wiring
for information)

OPERATION​
The charging system is turned on and off with the
ignition switch. The system is on when the engine is
running and the ASD relay is energized. When the
ASD relay is on, voltage is supplied to the ASD relay
sense circuit at the PCM. This voltage is connected
through the PCM and supplied to one of the generator
field terminals (Gen. Source +) at the back of the
generator.
The amount of DC current produced by the generator
is controlled by the EVR (field control) circuitry
contained within the PCM. This circuitry is connected
in series with the second rotor field terminal
and ground.
A battery temperature sensor, located in the battery
tray housing, is used to sense battery temperature.
This temperature data, along with data from
monitored line voltage, is used by the PCM to vary
the battery charging rate. This is done by cycling the
ground path to control the strength of the rotor magnetic
field. The PCM then compensates and regulates
generator current output accordingly.
All vehicles are equipped with On-Board Diagnostics
(OBD). All OBD-sensed systems, including EVR
(field control) circuitry, are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trouble
Code (DTC). The PCM will store a DTC in electronic
memory for certain failures it detects. Refer to
Diagnostic Trouble Codes in; Powertrain Control
Module; Electronic Control Modules for more DTC
information.
The Check Gauges Lamp (if equipped) monitors:​
charging system voltage,​
engine coolant temperature
and engine oil pressure. If an extreme condition
is indicated, the lamp will be illuminated. This is
done as reminder to check the three gauges. The signal
to activate the lamp is sent via the CCD bus circuits.
The lamp is located on the instrument panel.

Refer to 8, Instrument Cluster for additional information.

INSPECTION​
The Powertrain Control Module (PCM) monitors
critical input and output circuits of the charging system,
making sure they are operational. A Diagnostic
Trouble Code (DTC) is assigned to each input and
output circuit monitored by the On-Board Diagnostic
(OBD) system. Some charging system circuits are
checked continuously, and some are checked only
under certain conditions.
Refer to Diagnostic Trouble Codes in; Powertrain
Control Module; Electronic Control Modules for more
DTC information. This will include a complete list of
DTC’s including DTC’s for the charging system.
To perform a complete test of the charging system,
refer to the appropriate Powertrain Diagnostic Procedures
service manual and the DRB
t scan tool.
Notice the last sentence above? To properly diag the KJ's charging system you need the DRBIII scan tool(or Starscan).
 
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