Alternator readings varying. 12 then 14
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Honda-Tech Member
Joined: Dec 2013
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From: Lincoln, MA
Alternator readings varying. 12 then 14
94 civic hatchDrove to work in the dark and rain and the electric system was not working well.
wipers were moving slowly. Dashboard lights were flickering. Speedo was dropping off to zero once in a while. Even temp gauge was reading a bit low, which I now think was electrical and not true reading as after charging it is back up to where it should be. battery was unable to start the car after work so I got a jump start and went over and had alternator tested at autozone and it read just over 12 volts so I drove with no radio and no lights and charged the battery overnight.
next day I went and got a used replacement alternator but decided to test the one in the car once more and it tested...14 volts...?!
fyi the cluster lights have been flickering for a quite a while now, wasn't sure what was causing this. Not sure if it is related. After I Pulled another alternator from another civic at the junkyard I also had that one tested too and it passed with 14 volts. This was a replacement for the one they sold me that I thought was bad but now am not sure(30 day warrantee) It looks better than the other one...cleaner and less resistance...Not sure what to do. Thanks!
also: is it easy to install a voltmeter on the dash so I can see what the alternator is putting out? Old cars used to have this, yes?
Thank you!
wipers were moving slowly. Dashboard lights were flickering. Speedo was dropping off to zero once in a while. Even temp gauge was reading a bit low, which I now think was electrical and not true reading as after charging it is back up to where it should be. battery was unable to start the car after work so I got a jump start and went over and had alternator tested at autozone and it read just over 12 volts so I drove with no radio and no lights and charged the battery overnight.
next day I went and got a used replacement alternator but decided to test the one in the car once more and it tested...14 volts...?!
fyi the cluster lights have been flickering for a quite a while now, wasn't sure what was causing this. Not sure if it is related. After I Pulled another alternator from another civic at the junkyard I also had that one tested too and it passed with 14 volts. This was a replacement for the one they sold me that I thought was bad but now am not sure(30 day warrantee) It looks better than the other one...cleaner and less resistance...Not sure what to do. Thanks!
also: is it easy to install a voltmeter on the dash so I can see what the alternator is putting out? Old cars used to have this, yes?
Thank you!
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Re: Alternator readings varying. 12 then 14
The yellow and black wire on the alternator 4 pin plug supplies power to the voltage regulator. It should have 12 volts when the key is on. If that circuit is not working you will get low and varying output voltage from the alternator.
Thread Starter
Honda-Tech Member
Joined: Dec 2013
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From: Lincoln, MA
Re: Alternator readings varying. 12 then 14
How do you test the voltage to the regulator? Does this happen to alternators sometimes...that they lose the ability to put out consistent voltage? I didn't think it could go back to 14... I was surprised by that
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Re: Alternator readings varying. 12 then 14
Bench testing the alternator also tests the regulator since it is built in. 14 volts is a proper result.
Backprobe the yellow and black wire in the 4 pin plug and turn the key on (no need to start). There should be battery voltage. Also the "battery" warning light on the dash should be on with key on engine not running.
Backprobe the yellow and black wire in the 4 pin plug and turn the key on (no need to start). There should be battery voltage. Also the "battery" warning light on the dash should be on with key on engine not running.
Thread Starter
Honda-Tech Member
Joined: Dec 2013
Posts: 197
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From: Lincoln, MA
Re: Alternator readings varying. 12 then 14
Battery light it on and door chime is dinging...
will try to figure out which slot is yellow and black.
Also: could it be a faulty fuse for the alternatir, maybe not fully blown but not wholely all together? Just wondering, as the dashboard lights have been flickering for a year or so if I recall. Or could that be part of it too?
will try to figure out which slot is yellow and black.
Also: could it be a faulty fuse for the alternatir, maybe not fully blown but not wholely all together? Just wondering, as the dashboard lights have been flickering for a year or so if I recall. Or could that be part of it too?
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