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1965 Impala SS Convertible
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330 Posts
Discussion Starter #1
I have a 92 lincoln towncar and the alternator light is stuck on even when i shut the car off...it kills the battery after sitting for a few days.I replaced the alternator because it was old anyway and i replaced the battery.Is there some kind of sensor that might be broke and is telling me its bad when its not?
 

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stupid light

i had a thunderbird "90" model with similar problem most of the older fords alt light are wired hot through key on but are not grounded at the dash, they ground through the alternators to complete the circuit lighting the lamp.Once the alternator is spinning fast enough to produce current the exiter post "usually red post or if in a plug will be hot with key on and should go of with key off" becomes hot and the lamp circuit has no ground and the light goes out. Is your alternator externaly regulated if so that could be faulty.Most parts stores can test them.of course look for damaged wires "kinked or bornt" if this all checks out I would look in the ignition actuator rack"in the steering collum. I had an 86 T-Bird that had problems there
 

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1965 Impala SS Convertible
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330 Posts
Discussion Starter #4
How do I tell if it is externally regulated?I bought a new alt. for it about 3 months ago because it went...about 2 weeks ago the light came back on...took it out pepboys tested and replaced it because it was bad,I put the new one in and the light remained on.I brought it back in and they said it was good.I put it back in today with a new battery and the light stayed on even with the car off. I drove it a half an hour to work and by time i got there it was completely dead...the light would barely work.I got the battery charged at napa so i could get home and it died again about 2 minutes from my house.
 

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Doc here, :pimp:

If you don't know for sure, call the dealer and ask..or get a manual for the car.

I have several Ford system schematics for that year but none for Lincolns..If it is internally regulated by system, there is nothing between it and the battery, to go bad (other than short) that would run the battery flat dead that fast..

Doc :pimp:
 

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1965 Impala SS Convertible
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330 Posts
Discussion Starter #6
Theres a wire running from the + post on the alt straight to the battery,theres a 3 wire plug running off to some were...on the 3 wire plug theres like a link that can be unplugged and when i unplug it the battery light in the car goes off.I also think theres a 2 wire plug.But I still think this new alt is bad because ive had problems with pepboys alts. before...bought a new one,it was bad,exchanged it,the new one was bad,and just got my money back.Theres a guy down the street from me who builds his own alts. and they actually last.i have his alts. in 2 of my cars with no problems now for about 3 years so im going to go there for a new one.
 

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1965 Impala SS Convertible
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330 Posts
Discussion Starter #7
and another thing....when the car is running,i pulled out the fuse for the radio and the alt. light went off but turned back on when i shut the car off with the fuse still out.
 

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1965 Impala SS Convertible
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330 Posts
Discussion Starter #8
I had the alt. tested and its good,checked all the connections,wires etc. and there good.you guys are telling me its the regulator if its externally regulated which i think it is.So do i have to buy a new one or...?Are they expensive?
 

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Doc here, :pimp:

You need to find out if it's externally regulated first..

Ask the dealer or someone local If it is..then there is some checks you can do.

Doc :pimp:
 

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1965 Impala SS Convertible
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330 Posts
Discussion Starter #10
I am going tomarrow to get it checked...well i was messing around with it anyway and coming off the alt. is a fat red wire that runs to a post on the power dist. box then from there directly to the battery.There is a three wire plug coming off of the alt. one of the wires coming from the 3 wire plug goes to a 1 wire plug that connects to the alt right next to the 3 wire one.So there are 2 wire left...they run to a link thats near the power dist. box.when i unplug the link the alt. light in the car goes off but doest charge the battery.The link goes to a giant thing of wires that run behind the radiator,behind the fender into the firewall area and thats as far as i got.Can you tell from my info if its externally regulated?I was also told that if you unplug the + cable while the car is running and it dies then the alt. is bad,so i unplugged while it was running and it died right away,is this test true?I had the alt tested at 2 places and it came up good.
 

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Doc here, :pimp:

GO TO THE DEALER, and FIND OUT if it is internally REGULATED...or ask where you bought the new one.I have 25 schematics for Ford, Lincoln and Mercury of that year...some were, some were not...that is the ONLY way you will find out, IF YOU DO NOT KNOW how to Visually Detect an EXTERNAL REGULATOR....I can't just tell you yes.


NEVER...NEVER!!!! Disconnect the battery cable on a running Vehicle!!!!!!!

You run the risk of destroying the Computer, The Body Control Module, The Powertrain Control Module, The Dura Spark Ignition, Any Digital Dash you may have, The CD player and power amp..

If the battery is in a state of H2S Gassing, the SPARK can cause an EXPLOSION and injure or Kill you!!!!!!!!!

The Battery Acts as a BIG buffer / Filter Capacitor To the System..A Defective Alternator CAN put out RAW AC voltage..If you remove the Battery while running , you send RAW AC into all the Digital, CMOS/HMOS units..This will Destroy them right on the spot..CMOS/HMOS and Linear Chips will NOT tolerate any AC on a source current line (power to the chip) They will heat and go into thermal Shut down (usually forever) IF they don't erase all the data on it.

An external regulator will look like a big finned Heatsink, with a plug and 3 to 5 wires coming out of it..that might be that box you found..MAYBE..

The Fuse link could also Be open Check that also.

To properly test the Alternator for State of Charge you put a DVOM across the battery, set for DCV, VX50 Volts or higher, with the engine warm and at Idle, it should be between 13.95 and 14.4 volts, If lower or around 12 Volts it is NOT charging..

Doc :pimp:
 
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