bosango Posted March 11, 2011 Share Posted March 11, 2011 Hi All, I was driving across Kansas in my '93 Legacy LS a couple of weeks ago when the charging and hand brake lights flickered on. When I reduced rpm, the lights went out. This scenario repeated itself for about 15 minutes until I stopped for the night. I though the alternator must be going so I bought a replacement the next morning to be safe and went on my way. I don't know if this bit of info is related, but at the time there was what appeared to be an electrically charged wind storm going on. I expected to have to pull over somewhere and put the new unit in. Well, 1,000 miles further down the highway and the warning lights never came back on. Now I can't decide if I should put the new alternator in or return it to the parts store (thank goodness for nationwide chains). Anyone have any thoughts on this? Was it just a weird Kansas anomaly? Quote Link to comment Share on other sites More sharing options...
Mike104 Posted March 11, 2011 Share Posted March 11, 2011 May want to check the battery terminals and clean them if needed. Also alternator wiring/grounds. Then start the car, and turn ALL electrics on and then run the engine to 1800 RPM and check the charging voltage at the battery and alternator output at 1800 rpm. It should be around 14V or so. (shamelessly stolen from Nipper at SubaruOutback.org). You may want to return the alternator anyway as I have heard some of the parts store ones are POS. YMMV Quote Link to comment Share on other sites More sharing options...
Suzam Posted March 11, 2011 Share Posted March 11, 2011 Was it raining or was the road wet when this happened? Did you check the drive belt? A wet pulley and belt could slip at higher RPMs causing the alternator output to drop. When dry or at lower RPM the belt would be able to catch again. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted March 11, 2011 Share Posted March 11, 2011 If it were me, I would return to the parts store with the new alternator. Ask the counter guy to test the performance of your current (old) alternator that is on your car. If your old alternator passes the performance test, then return the new alternator, and get your money back. Like previous poster said, check v- belt for tightness, as it could slip when wet. If so, just tighten the belt, or inspect the belt for wear, if bad, replace the belt. Quote Link to comment Share on other sites More sharing options...
eryque Posted March 11, 2011 Share Posted March 11, 2011 The "electrically charged wind storm" won't have any effect. If there was enough electricity in the air to disrupt your alternator, you'd be feeling like you were about to be struck by lightning. You're getting low voltage out of your alternator. This can be caused by bad connections, bad cables, bad belts, or a bad alternator. On a car that old, it wouldn't be at all uncommon if the negative battery cable is badly corroded where it connects to the frame. It's always best to diagnose the problem instead of guessing at solutions. So, either do like Mike said and test it your self, or do like Rooster said and have the parts guy do a charging system test. Personally, I like option B better because it's a more thorough test. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted March 11, 2011 Share Posted March 11, 2011 The "electrically charged wind storm" won't have any effect. If there was enough electricity in the air to disrupt your alternator, you'd be feeling like you were about to be struck by lightning. You're getting low voltage out of your alternator. This can be caused by bad connections, bad cables, bad belts, or a bad alternator. On a car that old, it wouldn't be at all uncommon if the negative battery cable is badly corroded where it connects to the frame. It's always best to diagnose the problem instead of guessing at solutions. So, either do like Mike said and test it your self, or do like Rooster said and have the parts guy do a charging system test. Personally, I like option B better because it's a more thorough test. Just a by-line to say that battery cable connectors do go bad. Just last week my car was driving fine with no issues. Then stopped for a bit, and could get no restart. The cars electrical system was completely dead. I traced it quickly to a badly corroded pos terminal. When I tapped on the terminal, the cable fell off the battery. This left me stranded with no way to attach the battery cable. I had no idea it was completely corroded, as the cable terminal is/was covered with a red rubber bootie, and out of sight. So, yea......check all battery and alternator wiring connections for trouble. Quote Link to comment Share on other sites More sharing options...
naru Posted March 11, 2011 Share Posted March 11, 2011 Sounds like an intermittent alternator diode to me. Simple low voltage/poor connections won`t illuminate the brake light. Another big clue is the lights going off w/reduced rpm. I`d install the new one. Quote Link to comment Share on other sites More sharing options...
bosango Posted March 11, 2011 Author Share Posted March 11, 2011 Thanks for the responses! I no doubt should have mentioned that I cleaned the terminals and posts about a week before the trip started. Also, though I was hoping for a loose belt, that was O.K. Finally, the charging system checked out fine at the parts place and with my own voltage across the terminals check. Yeah, that all should have been included in my original post. That diode bit sounds intriguing. Quote Link to comment Share on other sites More sharing options...
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