Alternator going out?
Alternator going out? Noticed yesterday at the end of the day after accelerating my "check gauges" light would come on then go off after a second. Today I saw why, after accelerating my voltage gauge would dip into the yellow. It progressed to the point where the gauge would hang in the yellow for a few seconds. Then the only time it wouldn't be in the yellow was when I was idling. Now after driving it just a few miles this morning it's in the yellow all the time. Blinkers blinked slowly and fuel pressure dropped 5 psi. Checked with a volt meter when I got home with negative probe on battery negative terminal and positive probe on back of the alternator it was at 12.07 volts with engine running. Looks like the alternator isn't charging at all and I'm running off 100% battery. Checked wire harness connection at back of alternator and it was snug, checked nut on alternator terminal and it was nice and tight. This was a new (not reman) AC Delco alternator bought in December 2015. Anything else I should check before going through the warranty process?
Make sure the single red wire is hooked up and working and not broken, etc. The red wire is the signal for charging of the alternator and it will not charge correctly without it being installed.
I would get the alternator tested at an autozone to be sure but it does sound like the alternator is going bad. If the alternator tests good then I would look to the red wire and make sure it has continuity all the way to the dash gauges.
Simply put a volt meter to the charging wire going to the battery and ground. It should read a STEADY 14.5 to 14.7 volts. If it's lower than 14.5 then most likely it's going bad. If the reading is jumping around then it's bad.
TECH Resident
Joined: Jun 2002
Posts: 943
Likes: 2
From: Houston
Don't just check the voltage for a second or two. Keep the multi-meter connected for a minute or so and check for any large fluctuations over time indicating a bad voltage regulator.
replaced it with a Napa reman unit and it seems to be doing fine now. Hptuners is showing a steady 13.1-13.2 volts. It really bugs me that a brand new AC Delco alternator burned out after 18 months.
Also as a kind of buyer beware PSA: that last alternator was from Amazon and although they eventually honored the warranty as per their policy concerning auto parts that are "shipped from and sold by Amazon" I still had to go back and forth between them and AC Delco customer service 4 times. Then was on the phone with an Amazon rep for 45 minutes while he consulted managers and supervisors and such. It would have been a lot easier to just go exchange at an auto parts store.
Also as a kind of buyer beware PSA: that last alternator was from Amazon and although they eventually honored the warranty as per their policy concerning auto parts that are "shipped from and sold by Amazon" I still had to go back and forth between them and AC Delco customer service 4 times. Then was on the phone with an Amazon rep for 45 minutes while he consulted managers and supervisors and such. It would have been a lot easier to just go exchange at an auto parts store.
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Verdad Gallardo I agreed with SS RRR. You should be around 14.5 volts with the car running. If it is really hot out it could be a little lower. Use a voltmeter and not the Hp tuners logger as the logger is getting the voltage from the PCM which is not directly from the source. There is much more resistance in the PCM reading than directly from the battery. If it still reads low, clean all the connections to the battery and alternator and make sure they are tight.
Staging Lane
Joined: Feb 2018
Posts: 94
Likes: 0
From: Bessemer City NC
thats a good test we always shot for 13.8 to 14.4 but thats about the easiest self test you can perform, you may try to turn on the loads and see what you get ie rear defog lights blower motor on high just to make sure when you load up the alternator it is not dying on you