1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Alternator Problem

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Old 06-04-07 | 05:10 PM
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From: Cali Baby
Alternator Problem

So Ive been absent for a bit trying to sell these strut bars and my car has been acting up on me.

I replaced my alternator with a second gen alternator, but that caused some problems....

When the car is cold and I get over about 3k rpm's my sub shuts off (loses power) and turns back on when the rpm drops. Also all my interior and exterior lights brightness fluctuates with rpm's.
<<How do I fix this?>> BTW: my sub has standard hook up to battery


Thanks,
Aure
Old 06-04-07 | 05:15 PM
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From: Oregon
Aure,
Have you checked to make sure your belt is tight and not slipping.

Also make sure that all of the grounds are clean, especially the one near the driverside strut tower.
Old 06-04-07 | 05:31 PM
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From: Cali Baby
If my belt were slipping wouldnt I be seeing a decrease in power?
When I rev it above 3K RPM my lights get really bright and I think my amp shuts off automatically so it does not short out.

In other words I think maybe the alternator is too powerful or something, maybe I need a bigger battery?

Im at work but i can check my belt when i get home.

Thanks,
-Aure
Old 06-04-07 | 05:38 PM
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From: Oregon
Originally Posted by resjsu
If my belt were slipping wouldnt I be seeing a decrease in power?
When I rev it above 3K RPM my lights get really bright and I think my amp shuts off automatically so it does not short out.

In other words I think maybe the alternator is too powerful or something, maybe I need a bigger battery?

Im at work but i can check my belt when i get home.

Thanks,
-Aure
You would not notice anything power wise from the engine. You would hear maybe a squealing noise.
If the lights are getting extremely bright then it is possible that the voltage regulator in the alternator is over charging and there is a protective circuit with your amp to shut it off to prevent damage. What does the voltage gauge read in the instrument panel?
Old 06-04-07 | 06:09 PM
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From: Cali Baby
The gauge is constantly changing. Once it passes the highest mark on the guage my amp shuts off and will only turn back on once the needle goes below the highest mark.

Even though it is constantly changing the needle is always pretty high.

- Aure
Old 06-04-07 | 07:54 PM
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Originally Posted by resjsu
The gauge is constantly changing. Once it passes the highest mark on the guage my amp shuts off and will only turn back on once the needle goes below the highest mark.

Even though it is constantly changing the needle is always pretty high.

- Aure
Either they wiring was done incorrectly or the regulator in the alternator is defective. You need to be careful because the amount that the battery is being charged can cause it to explode if any type of spark gets near that battery. Also can cause the headlamps and other bulbs to blow out from too much voltage.
If you go to change out the alternator or work on the vehicle, open the hood and vent it for awhile before you disconnect the battery.

Put on protective goggles and wear some good gloves as a precaution.
Old 06-05-07 | 10:31 AM
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The Alternator On Second Gen Cars Is More Powerfull Most Likely Because Of All The Electronic Doodaaads That Came In Those Cars If The Regulator Is Not Bad Then The Alternator Must Just Put Out Too Much Power For Our Cars! Keep Us Posted On The Situation
Old 06-05-07 | 10:28 PM
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Doesnt matter if you had a 10,000 AMP alternator in there,its only going to put out the power that is currently needed by the car's active systems and the battery's current state of charge.Thats usually is in the range of 20-50amps.It can be more or less if the battery is flat or you are/arent using a lot of electrical items.

I woulnt trust the stock gauge for accuracy,but if its hitting the top line on the voltage gauge,then you have an overcharging issue.I would definately not run the car until its fixed.If your pumping out 16-18 volts,you can fry your ECU,healights,stereo and anything else that is not protected from high voltage(like your amp).Get a multi-meter or some accurate tool to measure the voltage at idle,and watch it when you tap the throttle.It should never exceed about 14.5V when revved up.Ruling out grounds,bad wires,bad battery and other stuff,if the voltage swings up and down in time with the revs,youve got a bad alternator(voltage regulator). Many Kragen/Pepboy re-man alternators are crap and can fail often.Get a good unit.....same goes for starters.

Be sure the 2 wires on the back are hooked up right.Obviously,the big wire goes to the battery,but the smaller wires have to be correctly routed for the alternator to get its info about how much juice to make.The S4 alternator is a direct plug in (if I remember correctly).....the S5 alternator requires some mods.

I had an alternator lose its voltage regulator once,and it popped both headlights.The lights went radioactive bright for about 3 seconds,then burnt out.I had to drive home with highbeams and very,very low RPMS to keep them from popping.....good thing my engine is torquey!Im just glad it didnt fry anything else when it happened.
Old 06-05-07 | 11:56 PM
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Originally Posted by HEYTOYOTAGUY
The Alternator On Second Gen Cars Is More Powerfull Most Likely Because Of All The Electronic Doodaaads That Came In Those Cars If The Regulator Is Not Bad Then The Alternator Must Just Put Out Too Much Power For Our Cars! Keep Us Posted On The Situation
Old 06-06-07 | 12:08 AM
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Must be something going around......Ive been seeing that a lot.

Not that it really bugs me,but..... huh.......It Must Be Obnoxious,To Be Constantly Having To Hit The Shift Button With Your Pinky, Just To Write Incorrectly!...........yep,it is!
Old 06-06-07 | 07:41 AM
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How do you have the L and S connector hooked up on the 2nd Gen Alternator?

The way mines hooked up and been working is the S is suppose to go to a postive source the alternator knows what the current state of the electrical system is. I ran mine to the underhood fuses on the driver side strut tower.

The L is suppose to go to the wire that controls the "idiot" lights on the dash. Not sure which one that is, seeing that I have an SA its most likely different from the FB as well.

See Post# 3, this is what helped me.
https://www.rx7club.com/showthread.p...ght=ALTERNATOR
Old 06-08-07 | 02:40 PM
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From: Cali Baby
Damn. Still havent been able to check but there is no way I can stop driving my car!

Ill try the multi-meter and pray to god it is in range.

Will keep you posted.

Thanks
-Aure
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