Anakhoresis

iTrader: (1)

Now, to start off, I'm starting to wonder if it's not my alternator but instead my multimeter that's broken, so I'm going to see if I can borrow another one from someone as soon as possible to resolve that question. Car is an 86 AT GXL, pretty much all stock.

A while back the car was having odd misfiring issues, tested a bunch of things, found the alternator was giving off 16-18 volts. I replaced the alternator with one I had from a parts car, an 88 TurboII. It appeared to resolve the issues. However, driving it a couple nights ago after fixing an issue with the transmission (and I had not driven it for a while previously), I noticed when I pressed the brakes, the headlights and cabin lights dimmed, and the fan in the heater slowed down. I suspected the alternator. Now, unfortunately for some stupid reason I didn't test it before I pulled it out, but I pulled it out and took it to O'reilly's to get it tested. Apparently it passed all tests, voltages fine, 70 amps stable.

Brought it home, tossed it on... Experiencing the exact same issue with flickering lights (Also, I should mention there's no stereo and the cables are wrapped up so there should not be anything pulling much power). Decided to test the voltage... It's now reading at 18-19. I quickly tested tapping the brakes, which did not result in a voltage drop, then turned off the car to avoid damaging anything.

The dash voltmeter reads normal, but then again, it did even when my previous to last alternator died and it didn't start dropping until the very end, even though it was very obvious what was happening. It also bounces up and down sometimes so I don't trust it. But nothing seems to be out of the ordinary despite a theoretical 19 volts running through everything, which is why I suspect the multimeter.

Is there some way something could be shorting out my alternators somehow? As said, this is the third one I've put on there. Granted, besides the first that appeared to naturally die, the second and third were suspect (The second was the first one rebuilt, but I really didn't trust the mechanic), so I don't have a great control group for what's happening, but it does seem odd that it would test fine yet not only appear to be overvolting, but also not supplying enough power.

I know this was a right essay, but hopefully someone has stuck it out, and if so, any thoughts on my situation?

NYsNumba1Man

iTrader: (1)

All my lights dim at idle when i press the brakes, then my dash's voltmeter drops to around 12-13 if anyone else has something to add it would help a lot.

88_N/A_GXL

iTrader: (3)

NYsNumba1Man, does yours seem like it want's to die as well? Every time I roll up to a red light or stop sign and pop it out of gear and start to brake I have to watch my tach and occasionally have to heel-toe so I can stop and keep it alive. Maybe if I get the chance I could also look at my voltmeter and see.

It all started after I replaced the stock rubber brake lines with ss braided ones, and I'm thinking not pumping out enough juice to keep it alive. Then again, I can't really even have just the lights and rear defroster on without dipping to about 12 volts.

Off topic, what rims are those? I've got the same car, if my name didn't give it away already lol.

NYsNumba1Man

iTrader: (1)

Yeah, it shutters a bit like its about to stall and now and then i have to lightly tap on the gas and it'll go back to normal. but not when the car is moving....... When i'm stopped it'll do that. I heard it can be alternator problems or something about the brake booster line.

If i have my lights and defrosters on the voltmeter sits at 12 which is basically running off the battery so i'm expecting my alternator to go out soon.

Yeah i read your name and thought, wow ironic. I wish i could tell you what kind of wheels they are because i have no idea, they came with the car. I think they're like pepboys garbage or something.

88_N/A_GXL

iTrader: (3)

Well, I guess I should probably be looking around my local u-pull-it for a taurus alt and see if that fixes things. Also, there's no markings on those rims, if you still have them? I just like the look of those type of 6 spokes.

OP, I would do a voltage drop test on the ground side of the regulator. Any voltage drop (resistance) there will raise system voltage by the same amount. Also, check all those ground connections and wires. I'd even go so far as to test the voltage drop between your battery post and battery terminal. 1.5-3.5v indicates a huge amount of resistance, you should be getting between 13.5-14.5v.

philiptompkins

iTrader: (4)

http://www.ebay.com/itm/140640716715...84.m1497.l2649

NYsNumba1Man

iTrader: (1)

Is the taurus altenator a direct swap in? Or will fabrication be required?

88_N/A_GXL

iTrader: (3)

There's quite a few ways to go about it. Just search and you'll see. I haven't decided which way I want to go about it. Here's what I'm leaning towards though, just maybe not the breaker.

Thanks philiptompkins for the link, I woulda got around to checking there or the auto parts stores online for a new one eventually. I need to round up some money first lol.

Anakhoresis

iTrader: (1)

I'm thinking of going the Taurus route as well.

Could you perhaps walk me through a voltage drop test? I'm especially not sure by what you mean by between the terminals.

Anyway, I went outside today. Turns out the battery I had was dead (This is also worrying me, these electrical issues are going through batteries and they're expensive), swapped it out for a working one. At first, everything seemed fine. Started up with 14.8 volts at the battery, about 14.9 at the alternator. Then I revved it up though, and suddenly jumped to 15.6 at the battery, 16.7 at the alternator. Also rather interesting is that inside, using the power cable for the stereo I don't have hooked up, it reads 15.7 (battery voltage).

I turned it off, I'll try again later and see what it starts at and if it changes.

Not sure at all what is going on here. I was under the impression the voltage regulator is within the alternator? So theoretically if it's giving out 15+ volts the regulator is shot, yet it tested fine at the store...

More thoughts (and help on how to properly perform a voltage drop test)?

88_N/A_GXL

iTrader: (3)

Do you have access to a digital multimeter? If so, just turn the headlights on and take one of the probes and hold it to the battery post, and the other to the connector for that post. You want less than .1V or 100mV on the negative/ground side, depending on your range setting. It won't matter which way it's hooked up, it'll just have a - in front of it. Then, rinse and repeat for the positive side, then from the alternator b+ to the positive post, and finally from the case of the alternator to the negative post.

This should help us get a much better "look" at what you're working with in your charging system and we can go from there.

Edit: Missed the voltage regulator part. It can test fine at the store, but when you install it all the resistance, assuming that's the problem, would cause it to full-field, ie. stay on, more than normal and burn it up.

Anakhoresis

iTrader: (1)

Okay, so getting 0 when testing the battery posts/connectors, and when testing the Alternator B+ to Positive, it gets .07, and Alternator Case to Negative it is .01.

That's kind of what I figured about the store test. They say they'll test it on the car, but then you'd be out of luck if it failed on the way or on the way back.

Edit: Have to go to work now but will check later tonight.

88_N/A_GXL

iTrader: (3)

Those are very reasonable drops. Next, you're gonna have to work a bit out on your own cuz I can't go look at my car right now, but test ground side of the regulator to the negative for a voltage drop. There should be nothing there, then test the sensing voltage input to the regulator and it should be battery voltage.

Anakhoresis

iTrader: (1)

Sorry it took long to reply.

Yep, zero voltage drop for the first test. For the 'sensing voltage input', is that the same test as on the FSM where it says IC Regulator Power Source Inspection? It says to test the R terminal on the plug to get battery voltage, which if this is the correct test, it was.

I also did the L terminal voltage inspection which checks to see if it's between 1-3v with the key to 'On' and it was 2.61, so within spec (though it seems rather to the outside).

88_N/A_GXL

iTrader: (3)

In the FSM, are you meaning 5-8 Test 4? Then that's good. Now if you can run through 5-10 Test 1 step 6, unless that's where you were getting the original 16v+. It could be that those two alternators you have could just be showing their age and it's getting time for you to go the Taurus route.