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1993 Seville STS
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Discussion Starter #1
Hi all. I purchased a 1993 Seville STS recently. A couple of days ago it died because of a charging problem. It really looks like a bad alternator. Today I got the alternator, brought it to a parts store and they tested it as bad. They didn't have it in stock so I went to a local yard. They tested it a good,so I second guessed the first test. I then brought it to 2 other parts stores and they also tested it a bad. Of course now I don't know if I can trust the yard to test theirs as good if mine is actually bad and they test it as good. It looks like both the battery and alternator were replace in '06, the alt has a remanufacture date on it.

Sorry about the rambling, but I thought I would let you know a little about my frustration with this so far before I get to my questions. I did a search and found a couple of posts but no answers about the wiring. When the alt was replaced before it looks like the plug that goes into the side of the alt was broken. The person that did that job used some sort of glue to hold the plug in place. It also looks like the the plug may have been replaced or at least the "wire" repaired with a wire splice. I am concerned because the plug only has one small red wire, but the alternator has 4 prongs for this plug. I was unable to find any other wires in the harness along with the red one.

I guess this also has me concerned that the testing is not being done correctly if the stores are not using the same number of wires.

So I guess my questions would be:

1. How many wires are on the plug for my '93 Seville STS going into the side of the alternator?
2. Should the Alt have the 4 terminals and why don't all of them get used?
3. Does the plug itself have any internal resistors connecting 2 of the Alt terminals? I don't think this is true because it doesn't look like the there are any contacts for the extra terminals in the plug.
4. NAPA has a replacement connector (ECHEC101) but it looks like it has all 4 of the wires with it. Would this connector likely work using just the one to the red wire and taping off all of the others, or can you guys source out the correct one? (Sorry about giving just a part number for NAPA, I am too new to give a link to the part)

Thanks very much for your help.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
only 1 wire in the four position connector is used. Why? good question. It's another GM design to confuse us is my guess. that wire is for the IP warning lamp.
The way to check your alternator is to use a VOM and read battery Volts with engine running. it should read between 13.5 and 14.5 volts depending on rpm. if not, the Alt or Voltage Regulator inside the unit is bad. Could be the voltage regulator only that can be replaced in the unit, instead of getting a whole Alt. If the store/ junk yard has a machine that can spin the pulley fast enough in rpm, the voltage output would be 13.5-14.5 Volt too. 6 of one half dozen of the other, both could be lying to get you to spend your money with. It isn't rocket science to check it yourself.
napa connector should work, just use only the one wire needed, tape or cut the others off.
 

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1993 Seville STS
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3 Posts
Discussion Starter #3
Thanks a lot for your reply. Everything does point to the alt. I don't recall if I tested the voltage with the car running, but I know the voltage isn't going to be there. I can charge the batt fine with a charger and the batt holds 12.3 Volts when I turn on the lights. It just discharges when running and the batt then eventually dies. Like I say my only other concern was that silly wiring. I also need to go through the rest of the charging wires and clean them up well. I would doubt that the stores would lie about the alt, if it isn't the problem then something else is and they know that I would be back. It is possible that they don't know what they are doing though :-( The stores that I brought it to seemed to have a much more advanced testing system, and the junkyard had a more rudimentary system, I am not sure if this was the difference or if maybe it just did work for him?

So now I guess now I just need to decide if I trust the junk yard that tested it as good to be able to backup the one they have since they tested it as good also.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
I know the feeling. Budget dictates sometimes. Ideally, wouldn't it be peachy keen if money grew on trees? If you were skilled at taking it apart and fixing it, buy the junk one, I doubt if he'd need a core so that way you would have a spare for parts. Otherwise, go with the store one which likely has a warranty guarantee of some sort. If it doesn't last, you're covered.
 

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1993 Seville STS
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3 Posts
Discussion Starter #5
Thanks again. I ended up buying the alt from NAPA since I couldn't trust the junkyard to get it right. It was a ton more money than I wanted to spend right now, I need to put a transmission in my other car still (the one I get to drive). The NAPA I went to didn't have the replacement plug, but a different chain store did, so I was able to replace that also (you just need to make sure you hook up the correct wire, ask me how I know -- and I double checked it :) It all seems to work fine now puts out 13.5 volts at an idle -- well the Caddy says 13.5 but my voltmeter reads 13.7. You know they didn't design anything here with any extra room at all :-( The little access hole on the bottom to drop the alt out could easily have been cut an inch bigger! Oh one more thing always remember to put the transmission line back into the radiator, it pumps out 3 quarts of fluid fast :) Again thanks for your help.
 

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1992 Sedan Deville, 1984 Lincoln Town Car
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759 Posts
glad if I could help. I reread the beginning and had somehow overlooked that you took your alternator to 3 stores and they checked it as bad. obviously the junk yard was :cookoo:, so you surely did the right thing by not trustin them.
 

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1993 Cadillac deville sedan 1986 cadillac deville RIP
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1,498 Posts
Did you get this problem solved rockauto.com sell those harness for you alternator they are only a couple bucks
 
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