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Alternator not charging

Tiny
JOCKINSTEIN
  • MEMBER
  • 2001 MERCURY SABLE
Electrical problem 6 cyl Front Wheel Drive Automatic

Would it be the mega fuse? Alternator is new been tested again and is good. However, it is not charging on car.
Sunday, September 7th, 2008 AT 12:47 PM

43 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
There must be a bad connection somewhere are a blown fuse. Here are to guides and the alternator wiring diagram so we can do some testing.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

and

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-a-car-alternator

(Check out the alternator wiring and fuse panel diagrams below)

Please let us know what you find. We are interested to see what it is.

Cheers, Ken
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Sunday, November 26th, 2017 AT 8:06 PM
Tiny
SIXSHOOTER
  • MEMBER
  • 6 POSTS
  • 2000 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 130,000 MILES
2000 mercury sable 3.0 sov alternator does not charge the battery took to ford they said my alternator plug was bad replaced and still no charge car messed up about 5 alternators and 2 bats prior to taking to ford new reman still good but still not charging bat and battery is good any help please.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
There are 3 fuses in the system that will need checking, see pic for locations, start here.

Mark (mhpautos)
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
AGOBERT
  • MEMBER
  • 2 POSTS
  • 2003 MERCURY SABLE
  • 3.0L
  • V6
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
Ok I have a 03 Mercury Sable DOHC. I've replaced the alternator twice now and warrantied out the battery twice. Im still having charging issues. I've checked all the fuses including the mega fuse on the side of the fuse block under the hood. It has 12.1 volts on both sides of that fuse and at the battery. I can't figure out this problem for the life of me. Any help you may have would be very useful.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
With the engine running, what voltage do you have at the battery? Is the battery going dead?
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
AGOBERT
  • MEMBER
  • 2 POSTS
12.2 volts while running. Only goes dead while driving
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
There is no charge reaching the battery when running. As a result, the ignition system and other electrical components are draining the battery while you drive until it is dead. Remove the alternator and have it bench tested at the parts store you purchased it from. If it passes the test, then chances are you have a fusible link that is bad and not allowing the power to reach the battery.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
SHERRYHAYS1168
  • MEMBER
  • 1 POST
  • 2000 MERCURY SABLE
Electrical problem
2000 Mercury Sable 170, 00 miles

Acts like alternator is not charging. Has been tested 2x and checks out good. Any suggestions?
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Hi there,

If the alternator is working, then you will have to get the battery load tested to see if it is viable, mack sure that the terminals are clean and tight as well. Start here.

Mark (mhpautos)
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
DSQUARE63
  • MEMBER
  • 9 POSTS
  • 1998 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 110 MILES
We've replaced the alternator and ground wires - will not charge battery?
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Did you test the replacement alternator?
There are no guarantee used or reman alternators wuld be good.

At the alternator main mast, test for battery voltage. If voltage is not present or much lower than battery voltage, the connection between battery and alternator is bad.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
DSQUARE63
  • MEMBER
  • 9 POSTS
We have already checked the alternator - it is brand new. We have also checked the battery voltage connection.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Attached is a schematic of the charging system.

The followng must be hot at all times :

1. Yellow/White wire.
2. Orange/Light Blue wire. (Disconnect to test)

Is the charge indicator light showing when igniton switch is turned on?
Does charge indicator light turn off when engine is started?
What is the voltage at B+ (Yellow/White wire) when engine is not running?
What is the voltage at B+ (Yellow/White wire) when engine is running?
What is the voltage between battery terminals when engine is not running?
What is the voltage between battery terminals when engine is running?
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
DSQUARE63
  • MEMBER
  • 9 POSTS
Yes the light is on with key and runnin. Both wires are hot. And the voltage on all those questions is not running it is about 12.4 when you start it drops to about 10.6 and as it runs it drops
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Check the crank pully harmonic damper. If you have abnormal belting noises and the pulley on which the alternator drive belt is seated on seems to be wavy, the damper could be bad resulting in the alternator running at a lowe r than required speed due to slipping.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
DSQUARE63
  • MEMBER
  • 9 POSTS
That all looks good voltage doest go up either if you raise it up off of idle.I got it to charge 1 when I re did all the ground wire it jumped to 15.3 volts turned on headlights fine turned on rear defrost and it quit and I cant get it to do anything now
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
OLDHAMD
  • MEMBER
  • 4 POSTS
  • 1997 MERCURY SABLE
  • 170,000 MILES
I have a 1997 Mercury Sable and the low voltage light came on. I checked the voltage on the battery and sure enough the battery was not charging. I removed the alternator and had it checked, dead, so I replaced the alternator and the battery. The low voltage light went out but the alternator is not charging the battery. The voltage before start is 12.7 and after I start the car the battery voltage drops to 12.3. I have checked the wires for corrosion and shorts but I see nothing wrong. I checked the voltage coming out of the alternator at the terminal point (wire with bolt) and it is showing 12.3. Any ideas?
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Have the battery recharged and retest.

When charging voltage drops, it could mean the alternator is not turning at the required speed or it is bad.

Check for blown fuses.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
With the key on, any voltage at the I terminal at multiwire connector? I looked at info for a motorcraft generator.
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)
Tiny
DSQUARE63
  • MEMBER
  • 9 POSTS
All fuses look goods I will charge battery and do load test it would be nice if it was that but if u run the car till it dies from low voltage if u let sit for as while battery will chagre it self back up
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Sunday, November 26th, 2017 AT 8:07 PM (Merged)

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