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Discussion Starter #1 (Edited)
Hello all, I am new to this forum and new to owning a Z-car. I apologize if this topic has already come up in discussion, though I could not find it...

I have a 1986 300ZX Non-Turbo with an analog dash and 5-speed manual transmission that I picked up for $1000.

I am having some Electrical/Charging System problems though I am not sure of the root.

Symptoms: All of the idiots are off while idling but when the engine is revved they all light up. Battery/Washer Fluid/Brake/Coolant/Etc... The high and low beams both worked when I bought the car but now the low beams do not, and only one high beam does. I think the bulbs are probably blown now. Also, when I revved the engine all of the interior lights become much brighter, as will the one high beam. And, I have noticed the the Volt Gauge to the far right is at about 13 when idling, yet when revved to about 3,000rpms it will jump to about 17 almost 18 volts.
It has on several occasions when revved shut the stereo off and caused the horn to beep...

I am thinking it is maybe the alternator or maybe a bad voltage regulator?

If any of you have had similar problems and found a solution, I would appreciate the input.

Thanks,
-Roland.
 

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Power FC Z32
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Get a hold of a volt meter and with the car turned off test your battery. Do you get 12v.?

If it's less then 12v~9.6v. then charge your battery or replace it. Next after the battery is replaced or refreshed (9.6v.~12v.) start the engine and test the battery again. The output should 14.2v but if it's less then your alternator is bad and needs to be replaced.
 

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Discussion Starter #3
I did that on the way home from work at Autozone. The battery is only at half-capacity CCA because it is being over-charged and killed. It tested at 13.7v with the engine off and with engine running and revved to 3500rpm it showed 17.6v. So, I believe to Voltage Regulator on the alternator is bad.
 

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Power FC Z32
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I did that on the way home from work at Autozone. The battery is only at half-capacity CCA because it is being over-charged and killed. It tested at 13.7v with the engine off and with engine running and revved to 3500rpm it showed 17.6v. So, I believe to Voltage Regulator on the alternator is bad.
You are correct, bad alternator.
 

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Discussion Starter #5
It was the voltage regulator. Replaced the alternator and no more problems.
 

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I have the exact opposite problem, at idle all the idiot lights come on, and at higher revs they go away. I just took out the alternator today, and am gonna get it tested and rebuilt. Does this solve the voltage regulator problem? Or is the voltage regulator separate from the alternator? Thanks
 

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Discussion Starter #7
The voltage regulator is part of the alternator, it can be removed if absolutely necessary, but I'd just buy a refurbished alternator at Autopwn for $65. Mine was overcharging, yours is undercharging. Just take your out, have it tested if you want, and just buy a refurbished one with a warranty... Like I stated, it's only $65, just get it. Then again, have you even checked to make sure your alternator belt is tight? If it's loose it can cause strange problems.
 
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