Sometimes my Battery-light lights up dimly upon starting engine

[theNamesRuss]

The following video is about four and a half minutes long. All the main details are in the video, so, if you can, watch the whole thing to get a complete idea what I am going through with this.

Basically, I've replaced my starter more than a couple of times now. Each time the car starts great for around a month or so, and then, slowly, this battery light issue creeps in... Ultimately, the starter fails to start the car at some point... (usually anyway)

http://s245.photobucket.com/albums/g...tteryLight.mp4

This time, I've caught it in the act before the starter fails (if the starter is going to fail this time that is). I've neatly rewired the entire starter at this point. So, I would hope that the starter is no longer part of this weird process.

[SK VeeDubR]

Alternator belt slipping?

edit - just a quick guess. Never watched the vid.

[CajunSpike]

have you had the alternator tested? from what I know, that light is turned on/off by a blue wire to the alternator.

[tolusina]

In your video, at around 3:10, you say something to the effect of, if you give it throttle, the light goes away, you don't know why that should be.
That should be because it's made that way, sort of. Note that in your video, about every time the tach jumps over 1,500 or so, the light goes out, if the tach stays at 1,000 or so, the light stays on. I didn't watch the rest of your video, it's senior attention span thing...
Not all A1s or A1 alternators do this, but on the ones that do, consider it normal.
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I have a guess, based on my now gone '92 Cabriolet and '93 Jetta, VW built in a kludge of sorts to address this very 'issue", the programmed the IAC to briefly jump the idle speed immediately after start up, effectively masking the 'issue'.
On my '92, I occasionally had IAC issues with the car, but the car ran well enough otherwise I was able to put off addressing those IAC issues. While the IAC was dis-functional, I'd often experience the battery light on after start just as you do, a quick blip would shut it off.
Once the IAC was back to normal, the car blipped itself, I never saw the light while running again.
The 'issue' is as old as alternators on VWs, it's normal, not an issue, but a perceived 'issue'.

You could spend some quality time cleaning the IAC, testing the throttle position switches or sensors, or you could just get in the habit of blipping the throttle after starting to turn the light off.

I doubt that any starter issue is related to the battery light, except possibly the Battery Positive connection from the large starter post up to the alternator.
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With multiple starter replacements, um, give some symptoms please.
If it won't re-start (won't crank over, starter inop) shortly after being driven, I.E. heat soak conditions, a well secured exhaust downpipe heat shield (as from the factory) is essential, electrically, a heat soak relay is recommended, another fix as old as VW way back to the 6 volt days.

[pcm1978]

Some thoughts, and I'm no expert on this, but I do have an older cabby that went through 4 alternators before I (hopefully) figured it out. Apologies for the length of this post.

1. You might have a problem with the alternator exciter circuit. From what I understand, the car has a 12V switched source running from the ignition switch, through the alternator light, and then to the exciter terminal on the alternator itself. Do you have 12V at the exciter wire on the alternator, when the ignition switch is in the run position? This signal tells the alternator to start producing voltage. If the exciter wire isn't working on the alternator, the alternator will still start charging, if you rev the engine a bit to trigger it. Does the light go out if you rev the engine after starting?

I believe that the alternator, once charging, will push volts back through the exciter wire and dash light. If your car's wiring is in good condition, you should have the same voltage on either side (one side of circuit is from battery to ignition switch to dash light, other side of circuit is from alternator through exciter wire to dash light). Ideally, both are at 12V, so the voltage difference is 0V, and the light stays off. If your alternator isn't putting out enough voltage, you get the light. If your car has the console mounted voltage gauge, what is its reading during all of this?

2. Changing the starter had an effect. That tells me you might have an issue with the hot wires coming off of your alternator, or the wiring between your starter and battery. On my car, IIRC, the main alternator charging wires went to the starter, and then the starter was wired to the battery + terminal. My alternator charging wires looked okay at first, but they were actually showing resistance and had begun to melt their insulation. They were probably damaged when I had a defective alternator that was putting out 17V. (It was awesome, wipers were so fast and headlights were super bright, but it cooked my battery). I replaced these with heavier gauge wires and also replaced the positive battery cable that runs down to the starter. This was cheap, and fixed the problem mostly.

3. Bad grounds can cause any number of electrical problems. Replacing the main ground wires/cables including the negative battery terminal (there are many threads discussing the methods) is cheap and easy, and probably not a bad idea on a car this age. That is my next plan to fix the alternator light on my car, which still glows a bit when I run too many power accessories for my tiny 55A alternator.

Hope this helps, and good luck.

[theNamesRuss]

My experience with this particular issue (now some 6 months) is that once I have a glowing battery light happening, no amount of revving the engine will get it to quit. The only way to get it not to glow is to start the engine with a throttle blip -- even if that throttle blip happens just before turning the ignition, strangely enough. I know this is so about the revving not changing things because I have gone on an entire trip with all sorts of different engine speeds involved only to notice the dimly glowing battery-light at the end. The next day, then, the battery might struggle to start the car.

Now, if the engine is warm it doesn't matter if I blip or not, the engine starts with no glowing battery light -- as was demonstrated in the beginning of the video. That first shot was video taped with a warm engine.

The other thing that I've noticed with this is that right after I have installed a fresh new starter into the car, it really doesn't matter how I start the engine, the light does not glow. (meaning I can ignore blipping the throttle and it won't glow, cold engine or warm. But, after about a month or so, though, I start to see the dimly lit battery light if I don't blip)