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steroidchickens

180sx alternator question (attn auto sparkys)

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any help would be great as I'm racking my brain.

done some wiring.

car will start and run even with battery disconnected so alternator is running car, charge light is flickering on and off.

rev it up, car dies.

tried another (second hand) alternator

charge light still flickering but this one will run car.

checked all earths good (even added extra)

hooked up jumper leads to battery and charge light goes out.

 

multimeter tested thick white wire going into alternator reading 11.5 volts.

checked thick white coming out 11.4 volts.

checked lamp wire (thin white/red) 11.4 volts.

 

have tried running thick power cable direct to battery and linking thick white and white in plug as well as running test light between them to white/red. (try and excite biapassing dash) and test light flickers same as dash.

 

have even vice gripped big cable to alternator housing and ran direct to earth on battery with no luck.

 

got first alternator tested he said amperage is fluctuating but still reading 13v

 

could i have 2 dud alternators?

or is there a better trick to test in car.

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Check the Light wire with a globe test light, should light up dull and the dash light should also light up dull. Could have a bung bulb in the dash which will usually cause the alternator to not charge. But yeah, if you're running a second hand alt, could always be f**ked too.

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Definitely a globe type? Test light probe should be going to earth, sense wire will obviously light up bright because its straight battery power and the Light wire should act as I said before. MAY not light up very bright at all but the dash light SHOULD light up at least dull. This is while it is unplugged from the alternator of course.

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if i get battery jumper pack, earth housing of alternator, power both whites and run test light from power and other end to white/red and test with multimeter will that be enough to test while alternator is mounted to car? obviously while car is not running will sit at the voltage of jumper pack and while running the car will go above 13v?

 

might have to try that with another test light. although i use that test light to check power antennas (voltage through test light triggers antenna)

 

i think I'm just confusing the situation haha.

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You shouldnt be running the car without a battery. By doing so the alternator thinks the battery has zero volts and will boost up the charge to find +13v. This is called a voltage spike and if it spikes hard enough it can fry electrical components.

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The test I'm describing is to test that everything in the car circuit is ok, ie alternator plug is unplugged. You're just testing that the wiring on the car is ok. If all is ok (S displays battery voltage and L does as I described) then the car is ok and the alternators are the issue. If either part of my test DOESN'T do as described there is an issue with the car wiring.

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Apart from alternator itself and its wiring. The charging system also has a regulator, fuse, and relay. You may want to check those out too

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Where is the voltage regulator? I have actually heard of that problem before

That's the thing took first alternator to get tested and he said it was pretty bad but not completely rooted

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Regulator should be mounted on the alternator. To change it. It may be as easy as 2 screws. Or a bit more work if its inside the casing you have to open it up. Not that hard. Still screws. Just longer lol. Regulators stop working when the brushes are worn. Fairly cheap to replace from what i remember

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Given this is a 180sx and that you can run the car with the battery disconnected, my money is on both alternators being junk. Not only are they low-current alternators to begin with (75amp isn't a whole lot if you start running amps/subs/thermo fans), but even the newest ones are 16 years old. I've been there myself, whereby my alternator's regulator died (it's located inside the alternator casing and includes the brushes), and the replacement alternator turned out to be junk too. The second replacement worked a bit better, but still it struggles with fans and headlights running.

 

Another source of problems, which I have also had the joy of experiencing, is a cracked alternator fuse. By 'cracked' I don't mean blown, I mean metal fatigue that literally causes it to crack down the middle. The line was so thin that I didn't even notice it when I first checked the fuses. It was a common issue with the oldschool fusible links which would disintegrate but mostly look ok, but as I found out, it happens to more modern cars too. In my case the crack caused very erratic behaviour, whereby the alternator would cut in and out depending on the compression of the copper. A $5 replacement fuse from Repco solved the problem.

 

LeS13Fuse_zpsb1de3c05.jpg

Edited by pmod

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Regulator should be mounted on the alternator. To change it. It may be as easy as 2 screws. Or a bit more work if its inside the casing you have to open it up. Not that hard. Still screws. Just longer lol. Regulators stop working when the brushes are worn. Fairly cheap to replace from what i remember

There is no relay for an alternator. And the voltage regulator is inbuilt in this and from memory are not readily available in AUS.

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If it's the same snap on test light I have then it doesn't have enough load in the globe to bring on the dash light

 

Never leave a car running without the battery hooked up

 

Where abouts are you located ? If in sa I can bench test both alternators for you

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Regulator should be mounted on the alternator. To change it. It may be as easy as 2 screws. Or a bit more work if its inside the casing you have to open it up. Not that hard. Still screws. Just longer lol. Regulators stop working when the brushes are worn. Fairly cheap to replace from what i remember

There is no relay for an alternator. And the voltage regulator is inbuilt in this and from memory are not readily available in AUS.

 

Oh i shouldve mentioned. In general. The relay is part of the charging system for cars. I didnt mean for OP's car specifically. I dont know whether all cars have an alternator relays or not. But Just trying to point out a few parts he may want to check other than just alternator and wiring. Glad to be corrected when im wrong though. Always something new to learn

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