Weird battery light activity in 95 SC Auto... Help!! - TCCoA Forums
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post #1 of 7 (permalink) Old 03-15-2019, 10:26 AM Thread Starter
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Age: 45
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Weird battery light activity in 95 SC Auto... Help!!

So I was on my way home from work today and looked down to see the check gauge light was on (I was getting towards the 'E' on the fuel gauge. The low fuel light was on as well, so I thought this was normal. Several miles later, I look down and the check gauge light is now out, but the battery light was on! The car was running fine, no apparent problems noted. Towards the end of my 50 mile drive home, I was looking down and hit a bump, the light went out for a split second, then came back on. Still no problems with how it runs.

I stopped for gas on the way home, full tank, and get back in the car and the battery light is out. When I check the voltage at home, the idle voltage is 13.66-13.7, not changing at all when revving the engine. I have new terminals on the battery, the car starts and runs fine.

Any thoughts?

UPDATE: 3-15-2019: Light is back!!

So I don't think it is related to the fuel low light. I drove to work this morning and it came on as soon as I started it! Arghh! I did notice that when I revved the engine above around 2500rpm or so, it would go out. Or, if I was above 2100rpm-ish on the highway it would go out. I can sit there and watch it as I approach 2100rpm. It will start to flicker and then as soon as I hit that certain RPM, it goes out.

Yet, it still runs great! I am thinking maybe the voltage regulator on the alternator is going out. I doubt it is the original, have 172k miles on it (well, more than that as my odometer gear needs to be replaced as it isn't working).

Question is, if it is the alternator, knowing that the local parts stores sell mostly junk, I wonder if I should take it to a shop and get it rebuild / upgraded?


Thanks Everyone.
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post #2 of 7 (permalink) Old 03-15-2019, 12:31 PM
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That voltage is low for charging. Did you see how low the voltage drops when you start the car? The battery could be weak, drawing more current and the alternator can't keep up. The battery should be 12.5v when the car is not running, then when you start it, the voltage should not drop below 11.5v if it does you have a weak battery. If the battery is solid then I'd suspect the alternator. Can't speak to quality, where to buy or rebuild.
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post #3 of 7 (permalink) Old 03-15-2019, 09:21 PM Thread Starter
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Alternator on 95 SC shot..Need alternatives..Help!

Well, I brought my SC to my local Orielly's on the way home from work. They tested the alternator and it said it was bad. I guess it was putting out only 11.7 volts. So I guess I am in the market for a replacement. I have a local U-Pull-It that I can go to tomorrow, and have heard stories of the 3.8L Mustang (later new-edge style) having an alternator that will work, but heard that there may be some issues with the SC 8-rib pulley not working on it, sticking out too far or something). Can anyone give me suggestions on what to look for? I would like at least the same amps capability and can make minor mods for fitment.

Any ideas?
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post #4 of 7 (permalink) Old 03-15-2019, 10:28 PM
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Buy a replacement alternator for the SC .. it will come with an 8 rib pulley, no issues with fitament .. and the proper amp output. I thought the SC had a higher output alternator to begin with, so why choose anything else ?
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post #5 of 7 (permalink) Old 03-15-2019, 10:29 PM Thread Starter
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I went out this evening after letting my SC sit for a while. While off, I checked the battery voltage, and it was sitting at 12.15 volts. I start it up, it starts fine, and I check the voltage again, and at idle, it is charging at 13.86 volts. This seems kinda low to me. It gets interesting when I rev the engine to around 2800-3000 rpm. When I do this, the voltage actually drops, and very quickly to less than 12.5 volts. So, it seems like the faster the engine revs, the more the load on it, the voltage the alternator puts out seems to disappear. Bad alternator? Sounds like it. What do you think?
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post #6 of 7 (permalink) Old 03-16-2019, 05:08 AM
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yeah i think it was evident from the get go that the alternator was bad further verified by the parts store test and again by yours

I've had excellent luck with autozone alternators. Probably changed over 50 of them in my lifetime on various vehicles over the years and never had a single issue with a single one. Off the top of my head 3 or 4 of my supercoupes have had duralast alternators on them for years and have been completely problem free.

I will tell you though that a lot of people blow new alternators by loading them too hard. Ignorant people will use a brand new alternator to charge a dead battery and then blame the alternator for being defective when it fails. As long as you fully charge your battery when you change your alternator you'll never have a problem.
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post #7 of 7 (permalink) Old 03-16-2019, 01:09 PM
No, Mr. Lemmywinks, No!!!

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I bought one of these, and refurbed my original; $20 on amazon.

Victory Lap FDA-04 Alternator Repair Kit

You will want to look at the slipring, where the brushes ride, and make sure it is clean and smooth; some 220 grit sandpaper held to it while you spin it will work fine.

If the bearings are good, with no rough spots or play, you can skip those; just save them for when you will need them.

If you take it apart far enough to put in the bearings, hit the outer case with the Chrome engine paint; it looks almost as good as real chrome.
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