Question about 1999 Mercury Grand Marquis

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Dash battery light Comes and off,battery and alternator have correct amps

There are no codes on code reader. Battery has 13.5 amps and alternator is within specs. I'am thinking maybe the voltage regulator may be going.

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Check voltage with car off should be 12.7 check running should be 14.3 or better if not have alternator checked

Posted on Feb 14, 2014


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Posted on Jan 02, 2017

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SOURCE: battery light comes on and i put a new battery in

Could also be an exposed wire intermittenly contacting a ground. local auto parts stores are known to check alternators for free or close to it. get that and the regulator checked first. because finding an exposed wire is time consuming and a pain.

Posted on Sep 18, 2010

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SOURCE: I have a 2000 Mercury Cougar 2.5 engine...this

Sound like you may have cooked the driver in the PCM that grounds the alternator for it to work correctly. The PCM controls the regulator in the alternator. Sound like you may need a new PCM. SORRY.

Posted on Jul 03, 2011

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SOURCE: 99 sable won't start, replaced battery,starter,alternator, but still wont even crank. code reader also said map sensor so it was reset worked for alittle but now nothing

If the car does not have a security system, I would check for voltage at the starter from the battery and from the key switch.
The power from the key switch goes thru the neutral safety switch before getting to the starter.

Posted on Sep 08, 2012

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SOURCE: alterator on 2000 mercury cougar putting out almost 17v

Have it checked. Something in your car has already knocked out or removed the voltage regulator function in this second alternator. The alternator is running at max output as if it were being "full fielded": being run without a voltage regulator.
Apparently the first one did this also, if it popped a circuit breaker. Are you certain you hooked them up right?
Could a short cause this? I'm not sure how a short could override or knock out the alternator's internal voltage regulator.. Have your alternator wiring checked.

Posted on Nov 30, 2012

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SOURCE: alternators not charging changed alternator

I had the same problem there is a inline fuse on the red wire that comes off the battery the wire goes to the starter then to the alternater after the starter there is a black bow on the red wire run your hand down it you will find it its at the back of the moter it have 175 amp fuse unbolt it go to auto zone and they have them

Posted on Dec 24, 2012

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if you have replaced alternator and battery and belts are tight .but light is still on then you can go to a parts place and they can double ck your alternator to see if it is putting out the correct amps ,and then if your prob is solved you can disconnect battery for 2 or 3 mins and should clear light on dash.if not then take it to someone with hand held computer to clear trouble code

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