Weird battery light issue
01-09-16, 04:53 AM
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Weird battery light issue
Battery light came on in my '95 LS400 while driving down the highway. Battery tested ok, but autozone said alternator wasnt charging. This was a new alternator, so i pulled it out and brought it back. Bench tested fine
So I put it back in. There had been a PS leak, so I fixed that. Found a loose connection at the 120A fusible link, so I tightened it. All fuses check out OK.
Battery light's still on.
Everything on the alternator is tight and the connections were reinstalled with dielectric grease. I haven't recently jumped it or been monkeying with the electrical system. Any ideas as to what I should check? Should I idle it a while and see if the light goes out on its own?
So I put it back in. There had been a PS leak, so I fixed that. Found a loose connection at the 120A fusible link, so I tightened it. All fuses check out OK.
Battery light's still on.
Everything on the alternator is tight and the connections were reinstalled with dielectric grease. I haven't recently jumped it or been monkeying with the electrical system. Any ideas as to what I should check? Should I idle it a while and see if the light goes out on its own?
01-09-16, 03:43 PM
#2
I would not trust the Autozone bench test results.
I once had a bad alternator test good at our local Pep Boys, that was actually bad - although I was not sure of it until putting the new one made everything good.
It's a problem if you're needing to rely on a bad bench test to prove for warranty purposes.
I would get a voltmeter and measure voltage at the battery when the car is off / idling / revved at 2500 RPM. That should tell you more.
I once had a bad alternator test good at our local Pep Boys, that was actually bad - although I was not sure of it until putting the new one made everything good.
It's a problem if you're needing to rely on a bad bench test to prove for warranty purposes.
I would get a voltmeter and measure voltage at the battery when the car is off / idling / revved at 2500 RPM. That should tell you more.
01-09-16, 07:00 PM
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I would not trust the Autozone bench test results.
I once had a bad alternator test good at our local Pep Boys, that was actually bad - although I was not sure of it until putting the new one made everything good.
It's a problem if you're needing to rely on a bad bench test to prove for warranty purposes.
I would get a voltmeter and measure voltage at the battery when the car is off / idling / revved at 2500 RPM. That should tell you more.
I once had a bad alternator test good at our local Pep Boys, that was actually bad - although I was not sure of it until putting the new one made everything good.
It's a problem if you're needing to rely on a bad bench test to prove for warranty purposes.
I would get a voltmeter and measure voltage at the battery when the car is off / idling / revved at 2500 RPM. That should tell you more.
02-27-17, 05:02 PM
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ground cable
check the ground leaving to the alternator. sometimes after time the plastic heat shield over the bolt heats up if the connect isn't tight. gets hot and causes electrons to go crazy. try to move neg cable to see if you can get some play. a lot of times a new alternator doesn't come with a new screw. I came across a situation where after removing the bolt the cable wasn't seated correctly and had a crack. by placing 2 washers and reseating cable problem solved.one way to test is when battery light is on touch match to exposed neg cable from alternator with match. if it ignites find way to tighten connection
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