You may remember I posted a few weeks ago about intermittent voltage problems with my CS Alternator swap. I began the process of cleaning and replacing wiring as recommended. So far, I have replaced the battery ground cable and a couple other grounds, cleaning contacts on ones that weren't replaced. I have also cleaned and replaced a few splices in power wires under the decklid.
In doing this a piece at a time, I began to notice a trend, which seems to be holding consistent, even when work isn't done. It seems that when the voltage drops off, disconnecting the battery will "reset" it for some time. Let me explain...
The above work was done over the last several weeks, a piece at a time. Each time I replaced something, some times when I didn't, I put everything back together and fired up the car, and it appeared to be fixed. Sometimes for 10-15 miles, sometimes for several days and 50-100 miles over a number of starts. Since the problem kept coming back, obviously I didn't fix the problem, but I began to realize that the common denominator was that the battery was disconnected in each case.
A couple days ago, it stopped charging. Started the car several additional times--no charge. I disconnected the positive cable overnight and reconnected it--alt was charging. Several starts (no driving) and no problems. This morning I took the car to work (about 2 miles) and it was fine the whole trip. After I parked, I shut off the headlights and watched the guage slowly drop from 14 down to 12. I immediately shut the car off and restarted it...not charging. After about 3 hours, I went out and restarted it...not charging. I disconnected the negative cable this time, for about a half hour. Reconnected, and started the car up...alt is charging now.
Does this shed any additional light on the problem? I don't know if there's something in the Alt that would cause these symptoms. I also don't know where the 2 wires in the plug come from...is one connected to the computer, that could be flaky?
I am tearing my hair out with this. I want to get this problem resolved so I can take the car outside the city limits! Thanks in advance for any help!
Likely bad battery. Have it tested, preferably with one of the newer computerized testers.
CS alternators are designed to not turn on if the battery is too low. A weak bettery combined with weak wiring can easily activate this function.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurasic Park)
Ditto to what Ogre said but there may also be something wrong in the "L" lead circuit. The CS will not operate if voltage is removed from that lead. The 84 has resistance wire from ignition to the alternator and that may be opening up when heated. Or maybe a conversion adapter with a resistor was used and the voltage is too low. Next time the alt shuts down, pull the harness connector (engine off, ignition on) and check the voltage on the "L" wire.
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11:33 PM
May 26th, 2005
AndyLPhoto Member
Posts: 2420 From: Skandia, MI, USA Registered: Nov 2001
Should the L wire have 12V any time the ignition is on? Where is the other end of this wire? Since it is a "resistance wire," what does that mean should I want to replace it? It's evidently not just your garden variety wire.
Thanks for the replies! I'll keep looking into this as I have time, and keep this updated on what I find.
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09:08 AM
May 27th, 2005
spark1 Member
Posts: 11159 From: Benton County, OR Registered: Dec 2002
You shouldn't have to replace the wire if it's still intact. The wire doesn't have much resistance, only 10 Ohms. That was enough to limit current when it was connected to the field coil of the old alternator. When that wire is connected to the “L” terminal on the CS alternator, resistance must be added or damage may occur.
The CS will actually ground the “L” lead whenever a fault is detected. One fault condition is stopped rotation which is the condition each time the key is turned on until the starter engages. The minimum resistance required is 35 Ohms which would limit the short circuit current to less than ½ Amp. That’s still over 5 Watts. Most resistors used in conversion adapters have a higher resistance allowing a smaller (wattage) piece to be used. The maximum resistance that can be used is 560 Ohms.
The main thing is that there must be continuous voltage on the “L” lead for the CS alternator to function.
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02:03 AM
AndyLPhoto Member
Posts: 2420 From: Skandia, MI, USA Registered: Nov 2001
Thanks Spark. That's very good information to have. I never really understood this aspect before. I also need to check to make sure I've got the correct adapter on the car. I didn't specify when I ordered it, so now I'm wondering...
A plus for you...ogre already had a plus. I'll do some more checking and post what I find!
Andy
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10:22 AM
AndyLPhoto Member
Posts: 2420 From: Skandia, MI, USA Registered: Nov 2001
Okay...I just couldn't wait, so I may have found the problem. Apparently, when I ordered the alternator, they sent me the wrong wiring harness converter, with no resistance, so there's just the resistance of the wire. I just went out and measured it, and it shows about 12 ohms. So my suspicion is that as the alternator aged, this improper resistance has begun to take its toll, and it has begun to shut off more frequently. This should also explain, I'm guessing, why completely disconnecting the battery "clears" the problem temporarily.
Sound logical? After work, I'm off to Car Quest to try and get the correct harness.
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11:14 AM
avengador1 Member
Posts: 35468 From: Orlando, Florida Registered: Oct 2001
You might have the right harness it's just that it may be wired wrong. Look in the Ogre's cave for the correct wiring sequence. I had to redo my harness before I even installed it because it came wired wrong. I have had no problems since it was installed.
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11:53 AM
AndyLPhoto Member
Posts: 2420 From: Skandia, MI, USA Registered: Nov 2001
Actually, what I got was just the wiring harness with a pigtail--not an adapter. I spliced the wires myself, so I know it's done "correctly." It just happens that it doesn't have the 35+ Ohms that the CS130 is looking for.
Can I just splice in a resistor? It's either that, or buy the adapter ($27 from Napa) and another SI plug to replace the one I snipped off when I did the conversion.
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02:48 PM
spark1 Member
Posts: 11159 From: Benton County, OR Registered: Dec 2002
Just add a 470 or 510 Ohm, 1/2 Watt resistor. The indicator lamp sockets in CS applications usually have a 510 Ohm resistor across the leads to keep the alternator alive should the lamp burn out.
On an 84... There is a resistor but I don't know the value. If it is only 10 ohms then you'd want to add 30 ohms to get it up into the range the CS wants. You can go higher as long as the CS will turn on. Using a higher resistance would cut the current when the alternator is intentionally turning on the lamp either at startup or when there is a problem. Cutting the current lets you use a lower wattage resistor.
As a short term fix/test.... you could splice a marker lamp socket into the L wire and use a 194 lamp. You can get marker lamp sockets of various suitable types at most parts stores. Anything that will hold a 194 lamp sould do.
You could also reroute the L terminal thru such a test lamp/socket to any circuit that is hot in Run/Start to eliminate posible dash issues completely. The main supply wire to the ignition coil would be a good choice you can get at easy. (No I don't know exactly what wire that is.)
IF and it's a big IF....
If you can verify exactly what regulator is in the CS... you can wire the I terminal directly to a circuit that is hot in only run/start. This will turn on the CS no matter if the lamp is there or not. The I setup shown in my cave is used in the 87-88 L4 and I think the 88 V6. (I've never been able to check a 88 V6 to be certain.)
The problem is that there is no easy way to ID the regulator in most cases.
Unless you can be certain which regulator is in the CS, DO NOT attempt to wire that terminal. If you have an F regulator, you'll fry the altlernator and maybe other things.
[This message has been edited by theogre (edited 05-27-2005).]
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08:02 PM
PFF
System Bot
Sep 28th, 2005
AndyLPhoto Member
Posts: 2420 From: Skandia, MI, USA Registered: Nov 2001
For anyone who is interested, here's what ended up happening. First, the alternator was bad. I had purchased it on the internet, but had a local guy rebuild it. The diodes were bad, as well as the voltage regulator. While the guy said the low resistance on the L circuit wouldn't have caused the problem, I did want to get it within specs. I added resistance to the circuit, metered all the voltages, and installed the rebuilt alternator, and....nothing.
I checked all my wiring again, and finally just got frustrated because of all the time I'd been spending on it. Having other more important things to do (like get married) I parked the Fiero for a while. My wife wanted to get it running for me, so I finally took it to a local guy to look at. He confirmed my wiring was correct, and suspected a bad alternator. I had him pull it out and took it back to the guy that rebuilt it and asked him to check it. Tested out just fine.
So my only other option was that the pins in the wiring harness were not making contact with the alternator. I had ordered an adapter with resistance built in from a place in Grand Rapids, so I installed that, reinstalled the alternator, and now it's working beautifully.
So to summarize...The alternator was bad to begin with. Then after a rebuild, it didn't work at all due to a bad contact in the plug. Thanks for all the replies and help...I learned a lot about CS alternators while troubleshooting this problem!
