Alternator wiring diagram?

Tiny
CARADIODOC
  • EXPERT
Be sure the voltage regulator is bolted solidly to the body too. It needs a good ground to work.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
BACKYARD MECHANIC
  • MEMBER
What does the I terminal (green with red stripe) of the regulator do? With ignition switch in run and nearby connector disconnected, the green w/red stripe wire has 11.7 volts (battery at 12.1). Reconnect the regulator and it drops to zero volts! Also it was red with blue stripe that has 0.1 volts while car runs and white with blk that is zero volts.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
Sorry to leave you hanging. Have you solved the problem yet? The green / red wire provides the turn-on signal for the voltage regulator. With the plug disconnected you'll be reading the 12 volts that comes through the ignition switch and dash warning light, (or a resistor that replaces that light on some cars). It went to near 0 volts when plugged in because the regulator was grounding that wire to turn on the warning light. When the system is working about 6 volts appears on the white / black wire to tell the regulator to turn the warning light off. THAT'S when you should again find full battery voltage on the green / red wire.

Look for a yellow wire in the connector. It should have full battery voltage all the time. If it doesn't, a fuse or fuse link wire is blown.

That connector is part of the voltage regulator. It's held on with four small bolts in a rectangular pattern. If you can see back there, you'll find two additional bolts. One might be covered with a plastic cap. The other one has printing stamped next to it that says "Ground here to test". Use a piece of wire to ground that bolt while the engine is running. If the headlights get brighter and the system voltage goes up, the regulator is defective and can be replaced separately. If there's no change in system voltage, further tests will determine the cause but worn brushes are the most common thing to find. They come as part of a new voltage regulator. I can walk you through the testing procedure. You'll need an ohm meter or test light.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
KRISTAKAPP
  • MEMBER
  • 1989 LINCOLN TOWN CAR
Electrical problem
1989 Lincoln Town Car Automatic

WITH GOOD BATTERY CHARGED THE CAR STARTS AND RUNS FOR 1/2 HOUR THEN DIES. ALTERNATOR AND BATTERY TESTED GOOD. WHEN RUNNING IF YOU DISCONNECT THE BATTERY CABLE IT DIES?
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
WRENCHER1
  • MEMBER
The charging system is not working and you need to determine why.
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-2
Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
BACKYARD MECHANIC
  • MEMBER
Hey thanks for getting back, the problem continues. I work retail, getting time away from my store is hard this time of the year. The regulator is external of the alternator, mounted on the wheel well. I don't see anything that says ground to test. I will check yellow wire this afternoon. Thanks again!
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
KRISTAKAPP
  • MEMBER
That is what we are trying to figure out. Any ideas of where in the charging system? Where else should we look?
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
There's two different generators for your car. I got sidetracked searching for a diagram with the correct wire colors on the external regulator version. For now, jumping between the "I" and "F" terminals on the regulator will bypass it and "full-field" the generator. Those should be the first and fourth terminals. That will make it charge wide open if the regulator is at fault. Don't raise engine speed and definitely don't disconnect the battery when doing the full-field test. Either of those things will allow system voltage to rise to dangerous levels if the generator is working.

If bypassing the regulator makes the generator work, you'll see the head lights get noticeably brighter, or, if you're monitoring battery voltage with a digital voltmeter, you'll see the voltage go up to around 14 to 16 volts at idle. That will prove everything other than the regulator is working.

If bypassing the regulator causes no change in output voltage, the problem is in the generator or wiring. I can walk you through that diagnosis once I find a diagram.
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+1
Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
AGGHHH! Do not disconnect the battery with the engine running! That was a poor man's trick done many years ago by mechanics who didn't understand how charging systems worked or how to diagnose them. The battery is a key component in regulating system voltage. You are lucky your generator isn't working. If it was, and you raised engine speed, it is possible for the output to go to over 30 volts. Computers can not tolerate that kind of voltage and the voltage spikes that are normally dampened by the battery. While a 1989 model might not suffer irreparable harm, newer cars can have up to 47 computer modules. If enough of them are damaged, the car may be not worth repair.

The place to start is by measuring battery voltage with the engine running. You must find between 13.75 and 14.75 volts. Based on the symptoms, expect to see less than 12.6 volts verifying the dead charging system. How was your generator tested? Also, can you describe the connectors on it? Do you have a plug on the side with two fat black wires with orange stripes, or do you have a single fat black wire bolted to a terminal on the back?

Caradiodoc
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
LEE.WILKERSON
  • MEMBER
Apparently there is a wiring modification for the alternator on this car. Ask your friendly parts supplier.
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-1
Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
SWEET DADDY SIKI
  • MEMBER
  • 1986 LINCOLN TOWN CAR
  • 5.0L
  • RWD
  • AUTOMATIC
  • 68,000 MILES
My AMP light came on the other day, so I connected my voltmeter to the battery which revealed 12.6 volts with the engine off. I then started the car and the voltmeter revealed 12.5 volts. I increased engine RPM to 2000 and the voltmeter still read 12.5 volts.

I removed the alternator belt, disconnected the negative battery terminal and gave the alternator pulley a spin. It spun freely. I then reconnected the negative battery terminal and the pulley spun, but not as freely as with the negative battery terminal disconnected. The pulley also does not spin freely when the ignition is in the 'ON" position. I once read that if the pulley spins freely with the key in the 'on' position, then it's either a faulty voltage regulator or the alternator brushes need replaced.

This is a 2G ( 2nd generation ) alternator. The voltage regulator is attached to the rear of the alternator & the brush holder is attached to the voltage regulator.

Could you tell me if this is could possibly be a faulty voltage regulator, or is it most likely a diode or stator issue? Should I replace the alternator?

Thank you
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
HMAC300
  • EXPERT
You really need to check output of alternator first which autoparts do for free. But also check if the fusiblelinks are any good that may be the reason as well.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CJ MEDEVAC II
  • MEMBER
THE EZist THING TO DO IS SNATCH "MR. ALTERNATOR" OFF AND HAVE A POPULAR AUTO PARTS STORE BENCH TEST IT

IF IT TESTS BAD, THAT'S PROBABLY THE WHOLE PROBLEM

IF IT TESTS GOOD, THEN YOU MIGHT NEED TO DIG DEEPER INTO CONNECTIONS/ FUSIBLE LINKS/ BROKEN WIRES AND OF COURSE, YOU HAVE ALREADY LOOKED AT THE FUSES!

IN READING WHAT YOU HAVE ALREADY DONE, I DID NOT DETECT THAT YOU SNATCHED THE BATTERY CABLES OFF WHILE THE VEHICLE WAS RUNNING. THIS WAS A TRICK FROM THE '70s ON BACK. YOU CAN REALLY DAMAGE SOME STUFF DOING IT NOW-A-DAYS!

THE MEDIC
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
EAWALT
  • MEMBER
  • LINCOLN TOWN CAR
My alternator on my 1988 lincoln town car keeps blowing. I replaced the elcetrial unit behind the dash that shows the clock and the flashing charging system at the advice fo my local dealer. But still blows the alternator out. What else could it be?
Help :(
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
LOVESCARS
  • MEMBER
Are you sure that your purchasing the correct amperage alternator. If you try to buy one that isn't capable of supplying the needs of the vehicle your esult will occur. Try buying a new alternator not reman. It's usually the voltage regulator that goes anyway.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
TJSDAD
  • MEMBER
  • 1985 LINCOLN TOWN CAR
  • V8
  • 2WD
  • AUTOMATIC
  • 13,000 MILES
Have replaced altentor, solnoid, starter. Was able to get car started. Charge System light still flashes. Battery was checked (12 plus volts). Battery hot terminal was getting hot untill I replacet starter.
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Monday, June 1st, 2020 AT 2:18 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Charge System light still flashes. Load test the alternator and double check connection at alternator and battery.

A good battery should be 12.8 volts when load tested should hold 9.6 volts in 10secs if not it needs replacement.
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Monday, June 1st, 2020 AT 2:18 PM (Merged)

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