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Charging issues on stock jzx81

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#1 hkp



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Posted 15 March 2017 - 11:19 AM

I have a 90 Cresta, stock motor with intake and exhaust, the p.o. had an issue with the car eating alternators, he took the car to a mutual friend who did some shit and installed a fuse, this stopped it from eating alternators, something to do with an exciter wire. P.O. installed powered by max multi gauge that shows Volts, oil temp and pressure, works great, I buy car knowing that car has a parasitic drag on battery, havent had much down time, I just pull negative lead when the car is going to sit overnight and put it back on when i leave for work. Here recently, the car has been acting like a dick head, I get in the car, fire it up, says its charging at 11.1v, run the car for about 5 minutes, then it shoots up to 14.5v and charges at that for awhile and then settles into 13.5v after a little bit of driving. This morning however, it didnt do that, it was charging at 11.1v then progressively got worse until it was "charging" sub 9v with the car slowly dying (not charging). I didnt have time to fuck with it, left in the driveway and grabbed ol reliable (03 RX8 with factory engine and 115,xxx miles) and I drove to work. I don't know shit about the charging circuit on this car so I figured I would ask here, it makes sense, I like being told I'm fucking stupid for not check blah. Any ideas? Also, when looking for parasitic drag, I used my multimeter on amps between neg lead and battery neg, I pulled fuse installed by P.O. to protect charging circuit and it was a substantial drop in battery draw, that would mean that somehow the charging circuit was drawing power when car is in key off position. 


#2 Gordo


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Posted 15 March 2017 - 12:05 PM

Stop being a broke-ass Cressida owner, buy an alternator....

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#3 hkp



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Posted 15 March 2017 - 12:20 PM

This the third alternator, something else is causing this.

#4 Demesio



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Posted 15 March 2017 - 12:44 PM

Bad battery could also fuck up your alternator...

#5 WhoreMouth_Jr


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Posted 15 March 2017 - 01:53 PM

Must be that time of the year.  Mine roasted my charge wires last week:




Completely unrelated to you, but I would maybe try big 4 upgrade? (big3 + a ground from housing to block/frame)


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#6 nojuan_here



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Posted 15 March 2017 - 05:04 PM

Where do you keep getting alternators from? Oreilly's, autozone? Those suck ass. They always seem to fail soon as you install them. Take it off, get it bench tested at your local parts store, get it warrantied or buy a name brand alternator (DENSO makes good reman units btw). The parts stores get theirs reman'd in Mejico, there's a reason they have lifetime warranties. Also check the belt tension.


Second is the parasitic draw still there? Normal draw should be less than 30 milliamps when the car is "asleep".

#7 hkp



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Posted 16 March 2017 - 04:44 AM

I'll check amp draw again tonight before I remove the alternator. 

#8 Okidriftjr


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Posted 20 March 2017 - 10:40 AM

This may help you troubleshoot.
The factory alt plug with three wires contain:
Exciter wire Fed from factory ecu (when metering should be close to battery voltage +-1%)

Charge lamp indicator which is a ground refferance (completes charge lamp circuit when alt is failing)

Sense wire (also should be close to battery voltage +-1%)

The exciter sure litterally turns the alt on and off
The sense wire is voltage feed back to the regulator. A low voltage value here should prompt the alternator to ramp up output current.

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