17 volts at idle!

[JiggaBro]

So 6 months ago I started to notice that my alternator output was a little low, being that it was the original i though 'might as well get a new one before it starts to die on me'
So I bought one from Oreilly's (Ultima i think)
Voltage was at 17v at idle and would climb up with rpm. Battery light would go on and stereo would shut off at 18v.
Needless to say I took it out in a heartbeat and replaced it. (lifetime warranty)

Second one was good... for 6 month. Then the bearing started to scream. So i replaced it and got the same overcharging symptoms as before.
I replaced the same Ultima alternator 3 times in one day. Needless to say, they gave me my money back.

I decided to try a different brand.... same thing happens!

If i put the original alt. back in, it charges fine (just a little low)
Im not sure what to do at this point. (and i really dont want to pay $370 for an alt. from the stealership)


On a good note, I can now replace the PIA alternator in less then 10 min!

 

[pasadena_commut]

So i replaced it and got the same overcharging symptoms as before.
I replaced the same Ultima alternator 3 times in one day. Needless to say, they gave me my money back.

I decided to try a different brand.... same thing happens!

Pretty unlikely that all of those alternators were bad. I had never heard of this particular issue before, but a bit of searching turned up that apparently in some cars bad connections to the alternator, certain blown fuses, or certain battery failure modes can result in the alternator putting out too much voltage. See for instance:

http://www.subaruoutback.org/forums...o-high-before-after-replacing-alternator.html

I would also check that all your grounds are solid, since iffy grounds can cause all manners of oddness.

Good luck.

 

[JiggaBro]

i just looked through the manual and didnt find any fuses that could be related to the alternator.
i also bought a new battery since the old started to leak.
im now confused with one of the connections on the alternator. I know that the 2 wire plug controls the regulator, but what is the other single wire with the ring connector? is that ground? i thought that the casing mounted to the bracket was already ground? or is it extra?

any other suggestions?

 

[GNO]

+1 on checking the grounds or even adding additional grounding straps/cables. Bad batteries will cause alternators to fail as well, and are often the culprit to overvoltage issues. Have you put in another alternator in since replacing the battery?

 

[JiggaBro]

I have tried 2 alternators since installing the new battery with no new results.

does anyone know what the cable with the ring terminal on the alt. is?

 

[GNO]

That should lead to the positive terminal on the battery.

 

[JiggaBro]

all ground cables are good and i even sanded them down.
nothing.

I think she's gonna see the mechanic for the first time

 

[i12drivemyMP5]

I've seen different things posted, those being...........

1)the ecu is the voltage regulator.

2)the alternator has internal regulator.

Symtoms you are having seem odd for it to be a ground issue since you are getting such different results between being a bit low with original and too high with multiple aftermarket. If it was ground issue it seems like it would act the same no matter which alt was in the car, old or new. For 170.00 for a new aftermarket or 300+ for a new oem you'd figure there'd be a damn regulator in there too, not just the alternator. Let us know how it turns out and what it took to get it right.....................

 

[JiggaBro]

the regulator things confused me at first too.
the ecu tells the alternator what the output should be, thus the 2 wire connector. That 2 wire connector is connected to the regulator, which is inside the alt.

im going to have to swallow my pride and take it to the shop.

 

[pkane]

Actually this happens more than it should and often are bad alternators. Were the alternators rebuilt? I would suggest getting it bench tested before installing. In fact you might consider testing at different stores (Oreilly, Autozone, Advanced, etc). Even though you are now fast at the install, if might be worth the effort. In my area the FLAPS are always close to one another.

 

[JiggaBro]

4 rebuilt alternators in a row being bad is just too hard to believe. And the all come with a big red tag that says 'do not bench test'

 

[i12drivemyMP5]

4 rebuilt alternators in a row being bad is just too hard to believe. And the all come with a big red tag that says 'do not bench test'

Yep, that's what mine said, do not test out of the vehicle......or something like that.