alternator not charging

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

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.

There are 3 fuses in the system that will need checking, see pic for locations, start here.

Mark (mhpautos)

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.

With the engine running, what voltage do you have at the battery? Is the battery going dead?

12.2 volts while running. Only goes dead while driving

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.

Electrical problem
2000 Mercury Sable 170,00 miles
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Acts like alternator is not charging. Has been tested 2x and checks out good. Any suggestions?

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)

We've replaced the alternator and ground wires - will not charge battery?

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.

We have already checked the alternator - it is brand new. We have also checked the battery voltage connection.

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?

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

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.

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

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?

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.

With the key on, any voltage at the I terminal at multiwire connector? I looked at info for a motorcraft generator.

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

Charging system wiring, below.

Yes, that indicates the charging system is at fault.

Have you confirmed the crankpully is good?

started car and no voltage on the I terminal

no i havent what just runn it and give it a visiual inspection spining

There may be a problem with indicator lite or wiring. The info shows a resistor to bypass the lite incase the lite-bulb vibrates out socket, or goes out. Does the charge lite on the dash work?

I've seen diagrams like this before, with the bypass, generator would not charge unless lite was fixed.

pully looks good some body told me the positive starter wire could b the prob 2 but that doesnt sound right

the light does not come on. It came on originally when I had low voltage on the bad alternator. I replaced the alternator and the light went out. I assumed it was because i fixed the problem. According to the owners manual the light should come on briefly when the key is turned to the on position. It does not! Is there a fuse I should be looking for to replace?

Engine Mechanical problem
1997 Mercury Sable 6 cyl Two Wheel Drive Automatic 134000 miles

Put new alternator and new battery but alternator fails to charge battery.Tested alternator wires at alternator and all were good. Checked the output with a voltmeter at battery, numbers started at about 14.2 and continued lowering. Wondering if the ecm completes the charging system or if for any reason could be the problem.

The voltage regulator controls charging rate. It's bolted to the back of the alternator. If you look at it, you will see the four mounting bolts, and two more in between them. One might have a plastic cap on it. The other one is labeled "ground here to test. Let the engine idle, and ground that terminal. Watch the charging voltage at the battery and at the output wire. If they go up a bunch, say to 15 - 18 volts, the regulator is suspect.

caradiodoc

Pully might look good but you need to confirm it is good. Looking does not confirm it is good as it can be deceptive.

Use marker to make a mark on outer ring of pulley an another near centeral ring and note if the outer ring moves away from the mark when engine is running.

" 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"

One of your reply mentioned this. The drop to 10.6 vlots, whare was it measured, between battery post? Was the voltage between the alternator main post and ground tested?

Starter cable is not involved unless alternator main wire is joined from there.

The fuse is in the diagram, goes hot/voltage with key on. If fuse is ok, use voltage tester at fuse leg, where the fuse plugs in.

it is the same at battery and on back of alternator

you are the man! replaced the fuse and alternator is charging the battery to 14.25 v

Thanks a lot.

Either the alternator or pulley is bad.

Glad you got it going your way. Hope the fuse doesn't blow again? Maybe it was the old generator that caused it to blow?

put marks all over pully they all stayed lined up i pulled the tree prong plug on back of alternator voltage stayed same at battery and touched the prongs in alternator with test light nothing then the plug the orange with a blue stripe barley light test light the other two nothing i did all that with car running on all my test the voltage at battery and at alternator have been the same

The Orange/Light Blue wire should have battery voltage. With engine off, unplug the alternator and test the Orange/Light Blue wire. If voltage is not avaliable or not battery voltage, check the voltage at alternator fuse # 26 in engine compartment fuse and relay box.

If battery voltage is available, check for poor continuity between fuse and alternator.

Try applying battery voltage to Orange/Light Blue wire and test if charging is as desired.

My car suddenly stopped on the freeway now it won't hold a charge. What problem causes this to happen??

Have both battery and alternator load tested-start here

My battery and alternator were tested. Its a rebuild though. I have also replaced the pulleys and belt. Everything is all on correctly. Something is just causing my car to die. It runs fine for a day or two after the repair but if I let the car sit then it dies.