Alternator wiring diagram?

Tiny
DENDEROSA
  • MEMBER
  • 1990 LINCOLN TOWN CAR
  • V8
  • 2WD
  • AUTOMATIC
  • 192,000 MILES
Changed fuse j10 P25 as suggested, no change. New battery still runs down with new alternator.
Ihave radio no power, fuse is good, engine idles up and down. Rear view mirror is removed and electric circuit is unplugged to this appliance. Also cd changer is disconnected. Does this make a difference? Where do I look for charging problem now?

updated 10-26-09
Thank you for your response, however I am unable to read the diagram you sent. It is too small. Also when you say disconnect the harness, there are two plug in type harnesses at the alternator. Which one do I disconnect and them to test the wire would that be at the harness side or at the alternator pins?
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Friday, October 23rd, 2009 AT 2:41 PM

37 Replies

Tiny
2CEXPT
  • MEMBER
Disconnect the alternator wiring harness and check for power at the light green and red wire do you have it? Below is your charging system wiring diagram.
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Friday, October 23rd, 2009 AT 5:39 PM
Tiny
2CEXPT
  • MEMBER
Disconnect the one with the light green and red wire-you check at the harness end.


https://www.2carpros.com/forum/automotive_pictures/12900_c1_16.jpg




https://www.2carpros.com/forum/automotive_pictures/12900_c2_14.jpg

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Monday, October 26th, 2009 AT 4:31 PM
Tiny
RICKMAR
  • MEMBER
Possible alternator ready to fry up and bomb out on you.
If you have Advance Auto Parts near you. Have them check your alternator. They will check it at no cost.
Good Luck;
Rick
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Wednesday, November 11th, 2009 AT 11:50 PM
Tiny
SJPD1959
  • MEMBER
  • 1990 LINCOLN TOWN CAR
  • V8
  • FWD
  • AUTOMATIC
  • 116,000 MILES
I have a 1990 lincoln town car with a 5.0L engine when I start up the car after a quater mile the dashboard lights go out the radio shuts off the heat shuts off blinkers don;t work nothing works but the car still runs when I shut the car off it won't start i'll jump the car and it starts right up could it be the altnator or voltage regulator is the regulator in with the altnator I need help fast I hope you can help me please thanks.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
KHLOW2008
  • EXPERT
Hi sjpd1959,

Thank you for the donation.

You need to perform a test on the charging system to verify if it is a fault with the alternator.

A faulty ignition switch or power interruption can also cause the symptoms described.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
BIRCHBAYBILL
  • MEMBER
  • 1990 LINCOLN TOWN CAR
1990 Lincoln Town Car

Digital cluster readout too dim in daylight. Do I neeed a cluster or could it be the voltage regulator?
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
JACK42
  • EXPERT
Most likely the cluster or the dimmer for the cluster. Remove the dimmer and use a test light to see if the feed wire changes when you dim or brighten it, if nothing the dimmer may be bad, if it works but dash stays dim th ecluster may need to be repaired or replaced
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
MOMALKI
  • MEMBER
  • 1990 LINCOLN TOWN CAR
Electrical problem
1990 Lincoln Town Car V8 Automatic

Hi,
I have a 1990 Lincoln Town Car and the alternator isn't working. I've checked on Fordparts. Com for the replacement part and was narrowed down to three options.

1. 65 amp with 65.4mm grooves
2. 65 amp with 50mm grooves
3. 85 amp

I'm not sure which one is the one I should buy to install. I bought the car used and the one currently installed on the car has no specs details on it.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
WRENCHER1
  • MEMBER
We can't tell you what alternator you have on your car but I can tell you as far as the first 2 go, you should be able to just swap pulleys to correct any problem there.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
TOWNY
  • MEMBER
  • 1989 LINCOLN TOWN CAR
  • V8
  • 2WD
  • AUTOMATIC
  • 70,000 MILES
Amp light came on, Replaced Alternator, Batt. Died two days later, replaced Batt. Batt. Died 2 days later again, took off new alt. And checked it. Checked out ok, but still not charging, Is there a in line fuse somewhere! HELP
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
Hi towny. Welcome to the forum. I think I can help you but I have to search for a service manual. Electrical is my specialty, and my sub-specialty is charging systems. Until I find a book, can you describe the generator? Does it have a rectangular plug on the side with two very fat black wires with orange stripes? Or does it have the voltage regulator bolted to the back with a white, yellow, and green / red wire?

Caradiodoc
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
TOWNY
  • MEMBER
Yes it has a rectanglar Plug with the two black wires with orange stripes, the other plug is a built in regulator?
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
Well, I found a book but the diagrams are really confusing. Can you tell me if your generator has an external fan on the front that you can push on with your thumb? Next, I think you have the 65 amp generator with the regulator bolted to the back. There's a three-wire plug on the regulator, with yellow / white, white / black, and light green / red wires.

If you have only a total of three wires, (black / orange, white / black, and orange / light blue), you have the 100 amp generator with an external voltage regulator. Since you have the more common dual black / orange wires, I'm using the 65 amp diagram.

Start by checking for voltage on the two black / orange wires. They should both have full battery voltage all the time. By the way. Those wires are never supposed to be unplugged because that will degrade the solid mechanical connection, and that will lead to overheating of the terminals and rapid failure. Replacement units come with a new plug already installed, and you are supposed to splice and solder the wires to the vehicle's harness. Weird, huh?

Next, the yellow / white wire in the regulator plug must also have battery voltage all the time. If it is missing, there is a fusible link attached to the starter relay. The wire has nothing in common with the starter circuit. It is just used as a convenient tie point. Of the six wires shown on that terminal, the fuse link is a gray 16 gauge wire. That is the weak link in the chain. The wire is smaller diameter than the main yellow / white wire so that's where it will burn open. The insulation is designed to not melt or burn. Test it by tugging on it. If it acts like a wire, it's ok. If it acts like a rubber band, it's burned open. You can buy replacement fuse link wire from the auto parts stores according to color. You can usually use less than half of the piece they give you so you'll have enough for another repair later.

Next, measure the voltage on the green / red wire. There should be 0 volts with the ignition switch off, less than about 1.5 volts with the switch on, (that terminal is grounding the dash light), and it should pop up to near battery voltage when the system is working. Battery voltage on both sides of the dash light turns it off.

Also, when the system is charging, there will be around 5 - 7 volts on the white / black wire. That voltage is tapped off the output and is what tells the voltage regulator to raise the voltage on the green / red wire to turn off the warning light.

Let me know what you find on those wires.

Caradiodoc
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
TOWNY
  • MEMBER
All fixed, I found a broken wire in the harnessjust off the alternator THANKS
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
AARON5775
  • MEMBER
  • 1989 LINCOLN TOWN CAR
  • 5.0L
  • V8
  • 2WD
  • AUTOMATIC
  • 188,000 MILES
Initially, charging light came on, change to interstate battery, re-manufactured alternator from advance auto, replaced positive cable leading from battery to solenoid, replaced negative battery cable leads to ground, (ground is to engine and body). I am at a dead end. Now the charging lamp flasher, also get a check engine light. Suggestions please.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
HMAC300
  • EXPERT
Check all the fusible links in picture one or all of them can be blown they will be on starter relay or where positive battery cable hooks up for check engine light, scan for codes. Get code get back to us with code. Connector is under hood.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
BACKYARD MECHANIC
  • MEMBER
  • 1989 LINCOLN TOWN CAR
  • 117,000 MILES
The "Charge System" warning message appeared on the message center. I assumed this was the alternator failing. I connected a battery charger and found the battery to be holding charge and 12.6 volts at rest. I bought an alternator from my local pep boys and installed. No difference - message still appeared and Batt not charging. Didn't realize but the 100 amp alternator has an external voltage regulator. Found one at my local Auto Zone replaced it. Still nothing - message and no battery charge continues. What do I do next?
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
Look for a blown blue 15 amp fuse. Next, measure the voltages on all of the wires while the engine is running, then holler back with those numbers.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
BACKYARD MECHANIC
  • MEMBER
12.1at batt and batt connection at alternator, at plug in connector the front wire (field possibly) 0.1 volts, rear wire (stator?) 0 volts, at regulator: I connection 0.9 volts, A connection 12.1 volts, S connection 0 volts, F connection 0.1 volts. No blown fuses
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Monday, June 1st, 2020 AT 2:17 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
Do you have wire colors to go with the voltages?

12.1 at the battery wire is correct. If there's 0 volts at the stator (white or white / black), that means there's no output. That tells the regulator to turn on the battery warning light. "A" is system voltage sensing and should be 12.1 volts. The field should be higher. The higher the voltage, the higher the current flow through the brushes and field winding. The higher the current flow, the bigger electromagnet it makes. The bigger the magnet, the more output current you'll get. With 0 volts on the field, there won't be any output generated.

When you measure these voltages, measure at the generator and at the regulator to be sure you have the same voltage on each end of each wire. If one has different voltages, look for a corroded wire or a loose terminal in a connector.
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Monday, June 1st, 2020 AT 2:17 PM (Merged)

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