New to the forum and new to Fieros, but a long-time fan of them, especially those with engine swaps. So, last week I picked up a nice, completed '87 with a '92 Deville engine and 5-speed Getrag. Runs great, but I have a slight drain thru the alternator. Previous owner said it was a recently installed reman. From my quick inspection tonight it looks like it has a three-wire plug plus the heavy battery lead running to the stud. Haven't yet pulled anything off yet to get a good look. CS130 I presume. Also, the gauge cluster has a voltmeter (shows around 13 volts w/engine running and cooling fan on), but no idiot light.
The question - how do you guys have your alternator wired? I've searched the forum, but haven't yet found anything clearly on point.
In any case, something on my alternator is clearly getting a constant, 12v from the battery when the engine is off.
Do you have a multi-meter? You need to set it to Amps, and put it in series with the battery with the engine shut off. Check the drain. It should be about 0.02A...any more than that and you do have a drain. Lots of write-ups (many recent ones too) talk about trouble shooting the drain if you in fact have one. Check the tech section posts over the last few weeks.
Many thanks for the welcome. Looks like a super forum. As to my alternator, I will search again for posts on this problem. In any case, yes, I've got a multi-meter and will get after this thing on the weekend and post again with results, etc.
Avoid the results that came up that are for the CS130D. That is a different alternator. The CS130 plug has one larger and three smaller terminals. The CS130D has four all the same size.
You should have constant +12v on the large red wire wired to the larger terminal. That IS how the alternator should be wired. The draw on that terminal should be less than 50mA. The alternator should not be making a noise due to the voltage being present on that terminal.
You should have 12v switched running through the bulb to the L (lamp) terminal. If the bulb isn't present, there might be a resistor hidden somewhere to emulate the bulb.
[This message has been edited by phonedawgz (edited 04-27-2016).]
Thanks, Phonedawgz. The google schematics will be helpful when I dig into this on the weekend. As you say, I have no bulb, but I do have a voltmeter in the dash. I have no idea where the PO might hae placed a resistor, but will look. The strange thing is, from what I can see of the alternator so far, it looks like the plug has only three wires, not four. The fourth wire is the heavy, red lead that first runs to the post, and then a lighter gauge wire from that terminal to the three-wire plug.
Faint Buzzing? Could it be the fuel pump still running? If the fuel pressure sensor is bad it can sometimes indicate "oil pressure" even when the engine is off and that will keep power connected to the fuel pump. You can test this by disconnecting the fuel pressure sensor and see if the noise goes away.
Faint Buzzing? Could it be the fuel pump still running? If the fuel pressure sensor is bad it can sometimes indicate "oil pressure" even when the engine is off and that will keep power connected to the fuel pump. You can test this by disconnecting the fuel pressure sensor and see if the noise goes away.
Thanks, guys, but the noise is definitely coming from the alternator. It is still receiving current when the key is off. First, I have to sort out the wiring to the alternator to figure out how the PO wired it. Then, if that seems correct, then I will suspect a bad alternator. Might a bad diode allow a drain like I am experiencing?
Ernie
[This message has been edited by Warlordsix (edited 04-27-2016).]
On an '84-'86 Fiero I'd suspect a faint buzzing noise with the key off to be a headlight motor not turning off properly. But I don't think there's that same issue with the 2nd generation headlight motors on the '87-'88 Fieros.
But you say the buzzing is actually coming from the alternator itself? Weird. My experience with a failed diode in a regulator is that the alternator simply doesn't charge properly. I've never heard a buzz.
You should have continuity from the gage fuse to terminal L (brown wire), and continuity from the Battery Junction Terminal to the small red wire and large charge wire. Key OFF with both checks. Terminal L will not have 12VDC until Key ON.
Thanks, again, guys. Patrick, this car has had the headlight upgrade installed, i.e. no motors, flush mount headlights. Olejoedad, the info you provided looks like it should really help. I no longer have a charge light, just the gauge/voltmeter in the dash. Does that make a difference regarding wiring to the alternator? Thanks, again.
Thanks, again, guys. Patrick, this car has had the headlight upgrade installed, i.e. no motors, flush mount headlights. Olejoedad, the info you provided looks like it should really help. I no longer have a charge light, just the gauge/voltmeter in the dash. Does that make a difference regarding wiring to the alternator? Thanks, again.
Ernie
If there is no light to provide resistance on the LAMP circuit, it is necessary to wire in a resistor. Sorry, don't recall the resistor value off the top of my head.
Okay, so here is what I've determined. PO wired the alternator as follows:
S Terminal - Hot w/key off. F Terminal - No juice w/key off. Ignition L Terminal - Hot w/key off. It is fed by a jumper that runs to the post on the back of the alternator (The post also connects to a heavy, red wire. It is direct to battery. P Terminal - Not used.
So, from the various schematics I've found online, I believe the problem is with the L Terminal. When used, it is to be used to a keyed source (with a charge lamp). If no charge lamp, then the F Terminal is to be used with the keyed source...but I'm not sure if F and L terminals are supposed to be used simultaneously. It's one or the other, I believe.
Ernie
[This message has been edited by Warlordsix (edited 04-29-2016).]
I've tried it both ways today. Hooked up and disconnected. The crazy thing is the alternator doesn't seem to work with the L terminal disconnected. With it off my voltmeter shows just under 12 volts, but with it hooked up it shows its normal 14 volts. My thinking is I need to find a keyed 12V for it, not the constant 12V it gets with it hooked up the way the PO has wire it.
BUT, I'm happy to say, with L disconnected from the constant 12V, the feint buzzing noise from the alternator goes away! I've found the drain.
Connect it to the brown wire in position B3 of C500. That is where it should have been connected. Your charge light will work, your battery won't drain, and your alternator won't buzz.
[This message has been edited by phonedawgz (edited 04-29-2016).]
