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how i think i killed my alternator


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yep, while stopped at roadworks I manually switch my twin cooling fans on for a moment and forgot to turn them off, not noticing until ninety minutes and same sort of kilometres later - highway driving. My fault also that I had not yet got around to hooking up the light in the switch :(

 

Notice the enter button hit here anybody ? :Flame:

 

Next night, after a few restarts, the red dash lights glimmered a little at idel, just once, enough to be an early warning, rather than something to shrug off and hope all is rosy.

 

I took note of my charge voltage or rather battery voltage doodad plugged into the cig lighter socket. It was 11.8 to 12.2 V for some time, then I noticed as I am using engine braking down a mountain, Voltage came good and started to read 13.5V for a quite a few more km.

 

restart it was back to 11.8 - 12.2 readout

 

The alternator is probably only 300,000 km old so I figure by running those fans for so long may have contributed to a bit of load on the poor old thing, or maybe coincidence, and likely find brushes worn so they just touching their contacts and likely die and let me down....so....swapped in a known trusty alternator and back up to 13.8V

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Trippy story... I got a grip of things wired into a aux strip KC Daylighters, CB Radio, Airhorn compressor, couple other things fricking cant remember lol! I figure eveything run on 12v.... I killed mine only because I zapped it, one or twice... it lived for about 6 to 9 months then slowly died. With out me really knowing no lights no nothing on the alertt something is wrong panel, suddenly over a 3 day period of driving just off battery power the dummy lights were fading on and off... one tough battery!!

Edited by Len Dawg
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Your alternator quit around or a little farther than all of my original OEM ones did.  Due to one of the brushes wearing down to where it doesn't contact the slip ring any more.

 

I am going by the mileage, and your description of the dash lights faintly glowing at idle.

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Omg.. mine died 3 weeks ago at 216k.

 

I got an ac delco reman from rockauto for 90 bills to the door. It was a direct replacement for the hitachi plug and play.

 

The worst part was it crapped out when I was leaving work at 3am in the dark. After 25mins to home my headlights were glow worms and the engine was stuttering but skoob got me home !

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not sure if Subaru intended to make all the dashlights faintly glow as the diodes in the alternator failed or it's just some coincidence in the way Subaru wired the dash, either way pissed me off whenever i would buy a remanufactured alternator, install it just to have the dash lights glow even brighter, thats why i would just change it in the parking lot of the autoparts store.

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Not that it has anything to do with the alternator but have you considered running power from your brake light sensor to a relay to power your extra fan? You can keep your switch for situations when you want your fan to just run. That way whenever you are stopped at a light or in traffic or wherever you stop it will be on.

Precisely !! Discussed this a few years ago with Brumby #2, this is #3

 

Was thinking a bit deeper by using a timer relay so that fans would only trip on after say 90 seconds of STOP lights on, to save them going on every time I tap the brake pedal. An anoying buzzer might be best :)

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Omg.. mine died 3 weeks ago at 216k.

 

I got an ac delco reman from rockauto for 90 bills to the door. It was a direct replacement for the hitachi plug and play.

 

The worst part was it crapped out when I was leaving work at 3am in the dark. After 25mins to home my headlights were glow worms and the engine was stuttering but skoob got me home !

Got one meself but cost 120 aussie bucks delivered. A new one was 80 plus 126 postage likely wrong side of USA through Rock. Still hoarding it

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not sure if Subaru intended to make all the dashlights faintly glow as the diodes in the alternator failed or it's just some coincidence in the way Subaru wired the dash, either way pissed me off whenever i would buy a remanufactured alternator, install it just to have the dash lights glow even brighter, thats why i would just change it in the parking lot of the autoparts store.

 

yes this is on purpose.  It's how they get all the lights to "prove" themselves at key on.  

 

They're are diodes so if individual other lights come on it doesn't light the "Charge" light, but if "Charge" light is on all of them will be.

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I think they do have some code to detect under and overvoltage. Last time I replaced mine the brake and charge light were solid glowing. Autozone put it on their tester and it was under voltage. I have lifetime replacements so it cost me nothing.

Edited by MR_Loyale
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I think they do have some code to detect under and overvoltage. Last time I replaced mine the brake and charge light were solid glowing. Autozone put it on their tester and it was under voltage. I have lifetime replacements so it cost me nothing.

 

It's not code.  It's voltage difference.

 

12v is applied to one side of the bulbs in the dash from key.

 

While running, the alt should also produce 12v to the other side of the bulb.  If the voltage on the output drops below the battery volts, the bulbs will come on via the voltage difference.  If they are dim, the alt is still trying but undervolt by a few.  So you on;y see a few volts worth of glow.

 

If they are on bright, then its a near zero output situation, so basically ground on the alt side.....so you see the full 12v brightness on the dash.

 

There is no "code".  No processor.  Just basic electrical principal.

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You can kill an alternator by not having both electrical connections in place.  The engine will run with the ground wire attached and the white plug not attached, but it will kill your alternator quickly.  Based on personal experience.

Done that before too :( The white plug had come out all on its own somehow. I think in its previous life the lock doodad had been broken or misshaped

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