OB99W Posted June 11, 2009 Share Posted June 11, 2009 I thought it was a little weird that the dash amp lite did Not come on when the alt. failed. I guess I'm just used to a dash gauges to give me an indication of whats going on under the hood. Personally, what good is the gauge if it's not doing it's intended purpose. But that's just me. The problem with warning lights is that they tend to be ''go/no-go'' indicators. In the case of the charge light, the alternator output has to drop sufficiently below the battery voltage before it will be lit. That means in some cases even if the output isn't enough to charge the battery, it still might keep the charge warning light from coming on. A dash-mounted ammeter would be much more revealing, but a voltmeter could tell you enough in most situations. Unfortunately, the ''average'' driver wouldn't know what reading was acceptable and what wasn't under various conditions. Quote Link to comment Share on other sites More sharing options...
Megell Posted June 11, 2009 Author Share Posted June 11, 2009 Glad you got the problem fixed. Glad we could offer advise. Happy Subie motoring! Thanks Rooster2. I noticed when I had the alt. off that there were two sensors. One looked to be a temp. sensor of some sort and the other looked like a sensor for the timing belt area. Do you know what these two sensor are? Thanks again, Mike Quote Link to comment Share on other sites More sharing options...
OB99W Posted June 11, 2009 Share Posted June 11, 2009 I'm not sure exactly what you were looking at, but the two might have been the coolant temperature sensor and the crankshaft position sensor. Quote Link to comment Share on other sites More sharing options...
Megell Posted June 11, 2009 Author Share Posted June 11, 2009 I'm not sure exactly what you were looking at, but the two might have been the coolant temperature sensor and the crankshaft position sensor. OK, I wondered where the crank sensor was. Is the temp sensor for the computer or the dash gauge? Quote Link to comment Share on other sites More sharing options...
nipper Posted June 11, 2009 Share Posted June 11, 2009 You dont want to rebuild the Alt yourself (as easy as it is to do). Last time i looked the price of the voltage regulator alone was almost double a rebuilt alt. Then the diode trio has to be replaced, the brushes etc. It is not hard to do, but it gets real expensive really fast. nipper Quote Link to comment Share on other sites More sharing options...
Megell Posted June 11, 2009 Author Share Posted June 11, 2009 You dont want to rebuild the Alt yourself (as easy as it is to do). Last time i looked the price of the voltage regulator alone was almost double a rebuilt alt. Then the diode trio has to be replaced, the brushes etc. It is not hard to do, but it gets real expensive really fast. nipper The last alt I rebuilt was probably a Delco back in the late 70's when I was making my living as a mechanic. I think we used to individually check each diode and replace as needed for just a few dollars. Or you could just get a rebuilt one for around $30. Good ol days. I hope these are not "the good ol days" with what the prices are by todays standards. Dealer wanted $274.95 for a factory rebuild. Mine was 120 today. OEM may be better in the long run. I'll keep an eye on this alt and hope for the best. Quote Link to comment Share on other sites More sharing options...
nipper Posted June 12, 2009 Share Posted June 12, 2009 Ok this being a 1991 (reread the lead post) I have no problem with you getting one from a commercial source. The issue is the 1995 on up legacies. Some stores sell you an imprezza alt as a legacy one, as they are way more exp and cant keep up with the load (been there personally). I cant see paying 200 bucks or more for an alt that on a car that "mature". Just dont get the 59.00 special. nipper Quote Link to comment Share on other sites More sharing options...
Megell Posted June 12, 2009 Author Share Posted June 12, 2009 Ok this being a 1991 (reread the lead post) I have no problem with you getting one from a commercial source. The issue is the 1995 on up legacies. Some stores sell you an imprezza alt as a legacy one, as they are way more exp and cant keep up with the load (been there personally). I cant see paying 200 bucks or more for an alt that on a car that "mature". Just dont get the 59.00 special. nipper So then the 95 up legacys are rated (amps) higher than the similar Impreza's? But the Impreza are more $ but with less amps than the Legacy Alt. ? The one I got today is rated a 70 Amps. I'm not sure what the book calls for and I didn't think to look at the old alt before I returned it. At least it was 120 instead of 59. ummm... Quote Link to comment Share on other sites More sharing options...
OB99W Posted June 12, 2009 Share Posted June 12, 2009 OK, I wondered where the crank sensor was. Is the temp sensor for the computer or the dash gauge? Hmmm, my brain apparently fell asleep when I initially answered your question. Besides the crank sensor, the other item easily seen when the alt is out is the oil pressure switch. The two coolant temp sensors are on the coolant pipe, and kind of buried. The one with a single-pin connector is the one for the gauge (referenced to ground), and the 2-pin one is connected to the ECU. Quote Link to comment Share on other sites More sharing options...
Megell Posted June 12, 2009 Author Share Posted June 12, 2009 Hmmm, my brain apparently fell asleep when I initially answered your question. Besides the crank sensor, the other item easily seen when the alt is out is the oil pressure switch. The two coolant temp sensors are on the coolant pipe, and kind of buried. The one with a single-pin connector is the one for the gauge (referenced to ground), and the 2-pin one is connected to the ECU. Thanks OB99W, good information to know if needed in the future. Mike Quote Link to comment Share on other sites More sharing options...
OB99W Posted June 12, 2009 Share Posted June 12, 2009 Thanks OB99W, good information to know if needed in the future.Mike You're welcome, although I hope you won't have to apply the info anytime soon. Quote Link to comment Share on other sites More sharing options...
kudd Posted June 12, 2009 Share Posted June 12, 2009 Just a thought and probably not related, but..... we changed the dash out on a '98 and the battery/alt light didn't get plugged back in. That is enough to keep a perfectly good alternator from sending charge to a perfectly good battery, thus draining said battery in less time than it takes to get to work with lights, wipers and defrost on. So, if anyone else has a bad alternator after dash work, check the idiot light connection. There ya have it from the peanut gallery. Quote Link to comment Share on other sites More sharing options...
OB99W Posted June 12, 2009 Share Posted June 12, 2009 Just a thought and probably not related, but..... we changed the dash out on a '98 and the battery/alt light didn't get plugged back in. That is enough to keep a perfectly good alternator from sending charge to a perfectly good battery,[...] It is ''related'' (although wasn't the cause in this case), and that's why I asked Megell (Mike) whether the dash warning lamps were operating correctly. In addition, it's possible for a blown fuse to prevent a good alt from charging a good battery -- the dash lights and certain electrically-powered accessories also wouldn't work then, but might be assumed to be symptoms of an alt failure, rather than that blown fuse being checked for. Quote Link to comment Share on other sites More sharing options...
Megell Posted June 12, 2009 Author Share Posted June 12, 2009 It is ''related'' (although wasn't the cause in this case), and that's why I asked Megell (Mike) whether the dash warning lamps were operating correctly. In addition, it's possible for a blown fuse to prevent a good alt from charging a good battery -- the dash lights and certain electrically-powered accessories also wouldn't work then, but might be assumed to be symptoms of an alt failure, rather than that blown fuse being checked for. I was surprised and disappointed that my battery dash light did not come on with a alternator not putting out enough voltage to run the car. I'm used to a light coming on letting you know that it needs attention. I just ever so barely made it through a very big, busy and dangerous intersection before the engine just died. That's what concerns me. If the amp dash light had come on, I would have had time to fix it before the surprise of a dead car on a busy road. I realized a battery can go bad without too much warning, but an alt. to fail without the amp light lighting up is new to me. Quote Link to comment Share on other sites More sharing options...
OB99W Posted June 12, 2009 Share Posted June 12, 2009 I can appreciate your concern. As I mentioned previously, the type of failure you experienced isn't that common. One possibility is that your alternator was still putting out something close to 12 volts, which would be enough to keep the warning light off, but insufficent to charge the battery. You might consider adding a voltmeter. There are some available that have adjustable visual/audible alarms for over- or under-voltage. Here's a link to one such gauge: http://www.glowshiftdirect.com/elite-7-color-volt-gauge.aspx . Quote Link to comment Share on other sites More sharing options...
Megell Posted June 12, 2009 Author Share Posted June 12, 2009 I can appreciate your concern. As I mentioned previously, the type of failure you experienced isn't that common. One possibility is that your alternator was still putting out something close to 12 volts, which would be enough to keep the warning light off, but insufficent to charge the battery. You might consider adding a voltmeter. There are some available that have adjustable visual/audible alarms for over- or under-voltage. Here's a link to one such gauge: http://www.glowshiftdirect.com/elite-7-color-volt-gauge.aspx . Thanks OB99W, I'll check the site out. I do remember taking a reading at the battery posts with car idling and old alt. and it read 12.3v prox. with not much difference in higher rpm. I always thought that my car, with a factory turbo, should have had gauges for the Alt. and Oil instead of just a light. And what's up with no turbo boost gauge or even a simple light? I still love the car though and I'll just do what I have to do to keep it running. Thanks again for the website. Mike Quote Link to comment Share on other sites More sharing options...
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