2001 mercury grand Marquis the alternator light comes on and off.just put in brand new one still doing the same thing

Asked by Apr 21, 2015 at 04:00 PM about the 2001 Mercury Grand Marquis LS

Question type: Maintenance & Repair

4 Answers

7,145

When installing a new alternator. You MUST first disconnect the battery or you can fry a brand new alternator in the first 30 seconds of the car running. If you didn't disconnect the battery first, you might need another alternator. Take it off and take it back to the parts store that you bought it from and ask them to check it for you to see if the diodes are fried. If it's OK then you have another problem. Check the tension on the belt and check if it's worn. That could be your problem, also check for loose or bad connections on the Alternator plug or wiring. Check your battery terminals also for loose or corroded connections. Good Luck, Kenny / MrBlueOval

1,515

Everything Mr Blue says is right on, Those belt tensioners go bad and should be replaced when the belt is replaced, but not always done. I'd replace them both, just for good measure.

7,145

One more thing I forgot to mention. I'll assume that your battery isn't completely dead but I'll address this issue incase others are reading this for help with their vehicle as well. A new alternator won't recharge a dead battery so if your (or anyone else's) alternator goes out completely and your battery goes dead, you need to recharge the battery first or you will also FRY your alternator in a few seconds (not in minutes) after starting the car with a jumpstart. Jumpstarting a car with a dead battery can ALSO FRY an alternator too. Jumpstarting should ONLY be done in an emergency when you are stranded in harms way. If you have access to a battery charger, do that first. An alternator (brand new or ten years old) will FRY it's diodes trying to recharge a DEAD battery so make sure your battery is FULLY CHARGED before trying to jumpstart a car. I just thought I would throw that in for others reading this post. Kenny / MrBlueOval

7,145

Obviously you won't need a jumpstart if you have a fully charged battery but I was trying to say to charge up the battery with a charger if you can first "instead" of jumpstarting. I'm Sorry if I didn't word that correctly the first time for those who didn't understand what I was trying to say. Kenny / MrBlueoval

Your Answer

Grand Marquis

Looking for a Used Grand Marquis in your area?

CarGurus has 1,575 nationwide Grand Marquis listings starting at $1,000.

ZIP:

Mercury Grand Marquis Experts

  • #1
    Tracy Hooks
    Reputation
    5,880
  • #2
    kbro
    Reputation
    2,190
  • #3
    Js08016
    Reputation
    1,940
View All

Related Models For Sale

Used Lincoln Town Car
17 Great Deals out of 1,626 listings starting at $2,450
Used Ford Crown Victoria
5 Great Deals out of 919 listings starting at $1,496
Used Chevrolet Impala
521 Great Deals out of 33,149 listings starting at $1,495
Used Ford F-150
3,205 Great Deals out of 226,288 listings starting at $1,250
Used Chevrolet Tahoe
885 Great Deals out of 39,489 listings starting at $1,799
Used Ford Mustang
437 Great Deals out of 42,783 listings starting at $1,488
Used Cadillac DeVille
3 Great Deals out of 1,422 listings starting at $1,988
Used Toyota Camry
1,082 Great Deals out of 75,995 listings starting at $1,000
Used Lincoln Continental
16 Great Deals out of 3,123 listings starting at $32,999
Used Chevrolet Silverado 1500
2,925 Great Deals out of 161,752 listings starting at $1,295

Used Cars For Sale

2010 Mercury Grand Marquis LS For Sale
6 Great Deals out of 85 listings starting at $2,990
2009 Mercury Grand Marquis LS For Sale
4 Great Deals out of 71 listings starting at $3,999
2008 Mercury Grand Marquis LS For Sale
7 Great Deals out of 108 listings starting at $1,000

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.