mentis Posted December 26, 2010 Share Posted December 26, 2010 On my way back from Christmas celebrations last night, my 93 Legacy L Wagon started to loose electrical power. I first noticed it when I realized that the instrument panel backlighting got very dim. Shortly thereafter the stereo turned off, so I pulled over to check things out. At the time, I was running the heater, stereo, lights, wipers, and back window defroster, so pretty much everything. After turning the car off, letting it sit for a moment, and then trying to restart it wouldn't turn over. I heard a repeated clicking noise so first guess was the solenoid. I let it sit for a few more minutes, and tried again. This time I noticed that the instrument panel backlight was back to full brightness, and the engine would turn over a couple of times, so something was changing. I waited and tried a couple of more times, and eventually power was back and the car started up again. Weird. Unfortunately, about five blocks away from home at 1am, the car started to loose electrical power again and this time the engine started to loose power (just as if I was running out of fuel) and finally stalled altogether. Even after waiting for maybe 30 minutes, it never got better that time. I came back this morning and got a parking ticket for Christmas , but the car started up just fine as if nothing happened. After doing some reading in this thread, I guess it could either be a relay or the IAC? Not sure though. This has never happened before, but seems to point to an electrical problem. All fuses check out okay, but I should probably check the alt, too? Any help would be greatly appreciated. Oh yeah, and happy holidays! Link to comment Share on other sites More sharing options...
Cougar Posted December 26, 2010 Share Posted December 26, 2010 It does sound like you are not getting a charge to the battery for some reason. I think there are fusible links used in your car's system so make sure they are making good connection. Also make sure the alternator fan belt is tight and check the wiring connections on the alternator. Make sure they are ok. Also clean the battery connections using a wire brush. It would be a good thing to have a load test done on the charging system to see how well it is working when you get the car running well enough. You may have to put a battery charger on the battery. Link to comment Share on other sites More sharing options...
mentis Posted December 26, 2010 Author Share Posted December 26, 2010 Yeah, I should take it in and have them test it, or maybe just get out my multimeter . I checked for corrosion and everything looks pretty clean and nothing's loose. Will double check the fusable links though and clean those as well. Link to comment Share on other sites More sharing options...
Olnick Posted December 26, 2010 Share Posted December 26, 2010 I came back this morning and got a parking ticket for Christmas , Man, what a bummer. That's even worse than my lump of coal. Link to comment Share on other sites More sharing options...
Cougar Posted December 26, 2010 Share Posted December 26, 2010 Since you have a meter make sure that the alternator is getting at least 13.5 volts to the battery while reving the engine slightly. You could also check for any voltage drop between the alternator output and the positive battery terminal. There should be less than .2 volts with a good load on the system. Link to comment Share on other sites More sharing options...
mentis Posted December 26, 2010 Author Share Posted December 26, 2010 Man, what a bummer. That's even worse than my lump of coal. Ha ha... I know, right? Since you have a meter make sure that the alternator is getting at least 13.5 volts to the battery while reving the engine slightly. You could also check for any voltage drop between the alternator output and the positive battery terminal. There should be less than .2 volts with a good load on the system. Thank you for the tips, I will do that! Link to comment Share on other sites More sharing options...
mentis Posted December 28, 2010 Author Share Posted December 28, 2010 Finally found my multimeter and was able to do some testing today. When I first tested the battery it was at just barely below 12 volts (around 11.92 I think). After turning on the car this did not change to above 13 as it should have. I then started turning on all the electrical components in the car one by one, and after I did I saw the voltage start dropping and it continued to drop till a little above 7 volts, which is when the car died. This pretty much seems like a bad alt, especially considering that I tested the voltage at the battery terminal and the alternator with the same results. Would you guys agree? Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2010 Share Posted December 28, 2010 (edited) If the battery warning light turns on when you turn the key from OFF to RUN then most likely the alternator is bad. If that light isn't working though then you need to see why that is. It supplies power to the alternator exciter and the light is in series with the power, along with other warning lights. You also need to make sure that the fused lead between the alternator output and the battery is good. If the voltages are the same at each point then you are good. I guess you did that already though. Edited December 28, 2010 by Cougar Link to comment Share on other sites More sharing options...
mentis Posted December 28, 2010 Author Share Posted December 28, 2010 Did not watch for the battery light, so will check that tomorrow. Also forgot to measure voltage of the fused lead, or rather I didn't know to do that. Is that the same as the fusable link in the fuse box? Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2010 Share Posted December 28, 2010 One of the fusible links does tie to the alternator output lead. If you measured about the same voltage at the battery and the alternator output then the fusible link is most likely ok. If there was more .2 volt difference then things need to be checked. Link to comment Share on other sites More sharing options...
mentis Posted December 28, 2010 Author Share Posted December 28, 2010 Yeah, the voltage was the same on both counts until I started to turn things on. So if I do need a new alt, I noticed on Rockauto that there are several brands and some that I hadn't heard of. Any that art generally good or bad ones to watch out for? Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2010 Share Posted December 28, 2010 I don't have any recommendations for brands but if there are any with a llifetime warranty I would go with that. Link to comment Share on other sites More sharing options...
mentis Posted December 28, 2010 Author Share Posted December 28, 2010 Good point ^_~. Thanks! Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2010 Share Posted December 28, 2010 You're welcome and good hunting. Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 28, 2010 Share Posted December 28, 2010 Did you first check to make sure the connections on the battery are clean and tight? Did you have the alternator tested yet? What about the battery? The alternator has a field wire that it uses to check system voltage. If the system voltage is too low (below 9v I think) it stops charging altogether to protect itself. If you measure 7v at the charge lead on the alternator, that doesn't mean the alternator is only producing 7v, as you are still measuring battery voltage when that charge lead is connected. (the other end is connected to the battery) You would have to disconnect the charge lead from the alternator to get an accurate measurement of alternator output voltage. But that won't tell you what amperage the alt is producing, and you need both voltage and amperage in order to charge. Right now the prognosis is not good for your alternator, but you don't want to put a new alternator in just to have a bad battery kill it in a month. If you have a battery charger, put a full overnight charge on the battery, and do your test again with it fresh off the charger. If the results are similar, the battery is bad. Link to comment Share on other sites More sharing options...
mentis Posted December 28, 2010 Author Share Posted December 28, 2010 (edited) Hmmm... I see. Will try that tomorrow as well, thank you for the advice. Would the auto-part stores run a better test on these components with their equipment? Edited December 28, 2010 by mentis Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 28, 2010 Share Posted December 28, 2010 They should be able to. As long as whoever does the actually knows what he/she is doing. The battery is typically under the most load during starting. Most places use a load tester that simulates the draw of the starter on the battery during cranking. Some of the new more advanced testers pull a smaller draw and measure voltage drop over time to determine if the battery is holding it's charge properly. Either one is just as effective. Alternator testers will measure voltage as well as amp output and make sure both are within range. If they know how to use the machine, they should test the diodes in the alternator as well. If it turns out you need one, 1stSubaruparts.com sells reman alternators for the 95 to 99 models for under $70. The part is the same except for the wire connector on the back of it. Snag a connector from a junkyard and splice it in and you're set for under $100 if you can wait for shipping. Link to comment Share on other sites More sharing options...
mentis Posted December 28, 2010 Author Share Posted December 28, 2010 Okay, cool. Of course this is assuming I can even get it there. So hey, that's a great deal on the alt. Why the huge price difference? The 93 model is $200 more! Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2010 Share Posted December 28, 2010 (edited) The alternator has a field wire that it uses to check system voltage. If the system voltage is too low (below 9v I think) it stops charging altogether to protect itself. If you measure 7v at the charge lead on the alternator, that doesn't mean the alternator is only producing 7v, as you are still measuring battery voltage when that charge lead is connected. (the other end is connected to the battery)You would have to disconnect the charge lead from the alternator to get an accurate measurement of alternator output voltage. But that won't tell you what amperage the alt is producing, and you need both voltage and amperage in order to charge. With all due respect to Fairtax4me these statements are a little confusing, to me at least. Let me go over these to explain some things the way I see them. The alternator has field windings inside it that build the magnetic field inside the alternator to produce the electrical energy needed for the charging. The field windings don't have some sort of protection against low voltage. The windings need to be excited by an external voltage to get the magnetic field started in the windings. This is provided by what is commonly called the 'lamp' lead and is tied to the exciter of the alternator. The external lead ties to the warning light in the dash. Power gets to the other side of the lamp leads from the ignition switch. This is why it is critical that the warning lamp be working so the exciter can do its job and excite the field windings. Once the process gets going then the external exciter power isn't needed. Voltage will build up on the exciter lead as the field builds up and eventually go beyond the battery voltage. This will cause the warning lamp to go out (alternator is working) since it now has about 12 volts on each side of it and very little current will be flowing. If the alternator has a problem the field will collapse and the warning light will turn on again indicating a problem. The field is controlled by a voltage regulator so it makes sure the output voltage stays within a certain range. As the battery voltage goes down the regulator senses that through the battery lead on the back side of the alternator and allows more current to be produced at the output to keep up with the load and keep the battery charged. Anytime the battery voltage goes below 12.5 volts there most likely is a problem with the charging system. It could be due to the alternator, a problem with the wiring external to the alternator, or even a loose fan belt. If a battery has a shorted cell condition that will cause the voltage to go low also and most likely kill the alternator if not caught quickly. Edited December 28, 2010 by Cougar Link to comment Share on other sites More sharing options...
mentis Posted December 28, 2010 Author Share Posted December 28, 2010 While I can't claim to understand this 100%, I do believe I get most of that. This leads me to believe that I still need to do some more testing before determining that it's the alternator. Planning on getting to that tomorrow. Thanks for the education ^_~. Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2010 Share Posted December 28, 2010 It should be pretty simple. If the lamp light is on it means the exciter is most likely getting voltage. If pulling the rear connector of the alternator turns the light off that is a good thing and the alternator is bad. If the lamp doesn't turn on then you need to find out why it isn't. There is a break in the circuit somewhere and you need to fix that before you can dertermine the alternator condition. Link to comment Share on other sites More sharing options...
Rooster2 Posted December 28, 2010 Share Posted December 28, 2010 All your symptoms point to a bad alternator. I don't think fusible links are an issue. Replacing the alternator is rather easy, if you are handy with a wrench. If car is no longer drivable, remove the alternator, then take to a parts store. They should be able to test with equipment in store to tell you if the alternator is bad. It is never good to have a break down. To break down on Christmas is a real bummer. I hope a replacement alternator solves your problem. Let's hope that 2011 is a good year for you. Link to comment Share on other sites More sharing options...
Cougar Posted December 28, 2010 Share Posted December 28, 2010 The biggest issue at this point is if the battery warning light is turning on. Link to comment Share on other sites More sharing options...
mentis Posted December 31, 2010 Author Share Posted December 31, 2010 All your symptoms point to a bad alternator. I don't think fusible links are an issue. Replacing the alternator is rather easy, if you are handy with a wrench. If car is no longer drivable, remove the alternator, then take to a parts store. They should be able to test with equipment in store to tell you if the alternator is bad. It is never good to have a break down. To break down on Christmas is a real bummer. I hope a replacement alternator solves your problem. Let's hope that 2011 is a good year for you. Thanks man . I've replaced alts before, so I'm hoping that's all it is. The biggest issue at this point is if the battery warning light is turning on. Did another test today. Turned on the car, then disconnected the alt and and battery light came on. So does this mean that it's not the alt? Link to comment Share on other sites More sharing options...
Cougar Posted January 1, 2011 Share Posted January 1, 2011 I think that is a good indication. The way I was thinking to check it is to just turn the key from OFF to RUN without starting the engine. All the warning lights should come on including the battery warning light. Then to verify there isn't a problem on the lamp lead disconnect the connector on the back side of the alternator. The warning lights should turn off then if there isn't any problem. The ground for the warning lights is made through the alternator. Link to comment Share on other sites More sharing options...
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