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CTMercuryTech
CTMercuryTech, ASE Certified Technician
Category: Mercury
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Experience:  Lincoln Mercury Factory Trained
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MY 2005 MERCURY MOUNTAINEERS CHECK CHARGING SYSTEM INDICATOR

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MY 2005 MERCURY MOUNTAINEER'S CHECK CHARGING SYSTEM INDICATOR LIGHT FLASHES ON ABOUT 2 OR 3 TIMES A WEEK NOW FOR THE PAST 2 WEEKS. TONIGHT ON THE WAY HOME IT FLASHED ON AND OFF REPEATEDLY. I TOOK MY TRUCK TO ADVANCED AUTO AND HAD THE BATTERY READ AND IT'S REALLY PERFECTLY. THE ALTERNATOR WAS REPLACED IN THE VEHICLE LAST APRIL BY THE DEALER. WHAT COULD BE THE PROBLEM?

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Before I can help you, I will need to know:

 

  • When you were at the parts store, Did they check the voltage at the battery with the vehicle running?
Customer: replied 6 years ago.
No, they just lifted up the hood and attached the cables I guess they use there to test the battery
It sounds like then they only checked the battery. They really should have checked teh output charging of the alternator at the same time. Eventhough you recently had teh alternator replaced, It may be bad again. I cant be certain without knowing the voltage. The battery should read 14.3-14.8 volts with the engine running. Anything above or below would indicate a bad alternator or cable going to the alternator. If the voltage is found to be good, I would suspect either a bad instrument cluster or a bad wire going into the instrument cluster. Hope this helps.
Customer: replied 6 years ago.

Thanks for your response. I just looked at the receipt for the battery test results and it says Good Battery Voltage 12.55V Measured 725CCS Rated 700CCA temp 42 degrees F and as I stated earlier, I didn't turn on the truck as the women indicated it wasn't necessary. I guess my question would be what would cause the alternator to go out in less than a year? Also, what is an instrument cluster? Will it be costly to replace?

Just because the battery tested good doesn't mean the alternator is charging properly. Most of the time the battery is perfectly fine and the alternator is no recharging it properly. Alternators no matter where you buy one whether it be a dealer or a parts store are a remanufactored unit. This simply means it is a rebuilt unit from an old one that was bad at one time. Not all remanufactored units are built correctly or bad parts are used when building them. The instrument cluster just sends a message back and forth with the alternator and computer and if it does not read the correct information it will put on the battery light. It is very rare, but internal problems of teh Instrument cluster can happen and unfortunally can be expensive at around $500-600 to fix. But like I said they are very rare and I just had to give you all the options for your problem.
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