Problem with 2002 Liberty Electrical

[wmerritt72]

I am at my wits end so perhaps someone here can help me. I have a 2002 Liberty Sport 3.7L V6. When driving on the highway at aboul 15- 20 miles in the battery indicator has started coming on. I Have visted the dealer and had the Battery and the Alternator changed, but the problem perisist. It happens no matter what is running on the electrical system. Also, it never seems to happen while driving short distances locally. Is there something else I should try looking into besides the Battery and Alternator? Any help would be appreciated.

thanks
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[NomadKJ]

Try hooking up a voltmeter or ampmeter to the charging system.
Voltage: 13.8 -14.8VDC
Charging amps: +
Discharging amps: -

 

[wmerritt72]

When my mechanoc Checked before it was charging between 12.75 and 13. The biggest problem is that When I take the truck to the dealer or a mechanic, the real big problem never happens. The mechanic even drove it around all day and it did not occur. Yet when I drove it a few miles to the mall, it happened again. Could somethig be overheating and causing this?

 

[abarkl]

Pull the fuse, bulb, or get out the electrical tape and cover the light!

 

[JeepJeepster]

When my mechanoc Checked before it was charging between 12.75 and 13. The biggest problem is that When I take the truck to the dealer or a mechanic, the real big problem never happens. The mechanic even drove it around all day and it did not occur. Yet when I drove it a few miles to the mall, it happened again. Could somethig be overheating and causing this?

I know what it is, your driving to the mall. :-s

 

[valvestem]

Voltage

When my mechanoc Checked before it was charging between 12.75 and 13. The biggest problem is that When I take the truck to the dealer or a mechanic, the real big problem never happens. The mechanic even drove it around all day and it did not occur. Yet when I drove it a few miles to the mall, it happened again. Could somethig be overheating and causing this?

12.75-13 volts is too low of an output, it should be closer to 14-14.4

 

[Neal]

12*1.2/=14.4

 

[wmerritt72]

After puyrchasing a new battery, alterneator and service manual. I am about to conclude the problem may be with the PCM. Since the voltage regulator is integrated into the PCM I may need to replace it. I am guessing this is what it could be based on the Servoce manual.