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Discussion Starter #1
Small problem I hope. :(
The other day my mian wire that comes off the alternator broke off at the alternator (3 wire altr). Found it and fixed it, now my gauge reads ok 14 volts instead of the 12 when it was broke. Now for the problem the idiot light on the dash is now on and will not go out. Have checked the other two to make sure they did not pop out and everything seems to be ok. :confused:
Anybody have any ideas where I start to look.

I hope this is not this years Woodward Ave stop me going problem
 

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With the key on and engine off does the light go out if you pull the alternator connector out of the alternator?
 

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Shaun;

I'd bet that the regulator got damaged when the battery was disconnected. Someone else here had that happen with an external Wells regulator, I think. It would charge but the light stayed on. In all likelyhood, you're looking at a new alternator (I believe the 72 is internally regulated??). The good news is that the 10SI's are cheap and readily available. Canadian Tire has a 5-year warranty Bosch alternator and you should find it's stock in London.

Do the test that John suggests first to make sure it's not the wiring. You can also ground the light wire (#1 terminal) to see that the light goes on and off when it's grounded but you've got to make sure you get the right wire because the other one is connected right to 12V and will be a short if you ground it.

Peter
 

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Discussion Starter #4
Thanks guy's I'll try and check it before I go to work tomorrow afternoon. I'll let you know what I find.
 

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The 72 is an externally regulated alternator but you have to move the vapor canister out of the way to see the regulator.
 

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Discussion Starter #6
Vapor canister, What vapor canister :rolleyes:
:D .
That regulator is on the drivers side almost beside the rad, right?
Well going to see if I have time to test things before I go to work.
 

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Part of the anti-pollution system. If the car has the vapor or charcoal canister it hides the regulator which is on the left side of the radiator.
 

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Discussion Starter #8
Originally posted by John_Muha:
With the key on and engine off does the light go out if you pull the alternator connector out of the alternator?
Answer is No.
Pulled what should be a double connector (had to put new ends on a long time ago)off and had a flash but the light never went out. The remaining wire has constant power to it at about the same level as the battery.
 

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Pull the connector off the regulator and see if the light goes out. Might want to remove a lead off the battery first because you might have to remove the regulator to get the connector off.
 

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Discussion Starter #10
Originally posted by John_Muha:
Pull the connector off the regulator and see if the light goes out.
With this done and the other wires still connected to the alternator, the light is now out.
Now what
:confused:
This kepts up think I'm going to move the computer out to the garage or the other way round. :D .
 

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OK, shows the blue field line isn't shorted somewhere. With everything plugged in and the engine running, you should see about 4 volts to ground coming out of the light colored (white?) lead on the alternator. This lead moves a relay inside the regulator and turns off the light.
 

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Discussion Starter #12
ok, this one is going to have to wait till tomorrow as I have to go work.
Thanks for all the help so far.
 

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John, what year did the cars change to internally regulated??

Also, try running it at 1000rpm with the lights on and see if it still generates 14V. Does this thing have an electronic regulator on it? I just can't see how a mechanical one can be charging while the light is on. It's just not really possible when you look at the internal mechanism.

Peter
 

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Discussion Starter #15
Peter I drove it all the way home from Turkey Point the day it happened. The drive home was at night and yes the gauge showed 14 volts all the way home. Lights never dimed at all.
 

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Discussion Starter #16
John I am having a problem finding the light coloured wire as my car is far from stock and a lot of things have been change over the years.
Do you recall what letter on the altornator it my be?
If you had to guess, which would you replace first the altornator or the regulator?
 

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The wires are next to each other on the regulator. One outside wire was blue. This is the “F” or field wire and goes up to the alternator connector. The one next to it on the regulator was white. This is the “R” or relay wire. This is the other wire that runs up to the alternator connector.

You want me to guess? Well, since I don’t think your car is original I think I’d spend the 20 minutes and convert to an internally regulated alternator which has both parts. The internal regulated SI alternator will probably cost the same as the DN alternator you have. It’s easier to troubleshoot later on because everything is contained in the same case.

If I was to guess I’d venture to say that the “R” or relay wire isn’t going high enough (>5 volts) to close the regulator relay making it an alternator problem.
 

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Discussion Starter #18
John I guess I should have read you post first
, but anyhow it turns out it was the regulator. I took mine off and when I shock it a little it rattled. So I drill the rivets out and a resistor looked like it had exploded in there. From what I know now this was a newer version as it had a printed curcuit in it. Got a new one (of the old style) and everything seems to be ok

Again
thanks for all yours and Peters help.
Just as a note when I priced this regulator out it raged from $85 - $22 (Canadian). I got the one for $22 and my alternator check at a small business.
 

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Doh, I was out by 1 year on the internal vs external


Shaun. glad you got it fixed. That's cool because I thought that it'd be electronic. I've got a mechanical regulator open here and it's impossible for the light to stay one while it charges.

I don't know what some parts placss are thinking. At $88 for the regulator you might as well spend $10 less and get a 10SI so it charges better and is more reliable. :D

Peter
 
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