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Voltage Surging/Spiking While Driving

fastasleep

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Jan 14, 2005
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Location
Christiansburg, VA
Over the past couple of months my car has started doing something that it has never done before as long as I have owned it.

I have a voltage gauge on my A-pillar. I was driving around town a few months ago and all of a sudden, my voltage went from ~14.4 to 18+ for a few seconds. It may have been much more, but all I know is that it pegged/maxed out my gauge at 18.6. It was like a drove through the Bermuda Triangle. I think I had the heat on at medium power and I noticed it was coming out with much greater force during the spike/surge.

It has happened a handful of times over the past few months at different times while driving. It seems to be completely random. It has done it at night with the lights on (they get much brighter...) and during the day without accessories on.

I had the alternator checked at Advance after the first occurrence and the readout said it was fine.

Any ideas what would cause this?

Could it be a belt/pulley issue?
 

Racah15

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Aug 28, 2012
Messages
315
Location
Colorado springs CO
Voltage regulator may be bad. I wouldn't trust "it's good". That's what they said about the crappy known bad starter I had them test, and a crappy known bad alternator I had them test. Try a good known OEM unit. Also, if it only happens sometimes, it may actually test completely fine.
 

fastasleep

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Christiansburg, VA
What is a voltage regulator? Is that a part of the alternator?
 

citymunky

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Chesapeake, VA
Yes it is inside the alternator.
 

Sir you will need a new Alternator. The voltage regulator is internal in the alternator.
Voltage spike can be extremely chaotic in the electrical system , luckily the battery takes most of these spikes as per design.
I highly recommend replacing the alternator asap before it wipes every computer and fires the wiring.
Good luck.
 

citymunky

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Chesapeake, VA
or you can buy a Voltage Regulator from Rockauto and replace it.
 

mikus

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Jan 11, 2007
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Aurora IL
+1 change this asap, and get an alternator from a respectable rebuild shop. it's well worth the extra few dollars.
 

prove_it

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Jul 3, 2008
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Sioux Falls, SD
Good rebuilder or OEM only. Even a delco alternator I put in died in only 6 months. The alternator heat cycles and causes failure in cheap off brand alternators.
 

fastasleep

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Christiansburg, VA
Thanks for the feedback guys. I will order an OEM one from the dealership tomorrow.

Blessings,

Ben
 

ktmrider

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Sep 10, 2007
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Location
Tempe, AZ
Quoting prove_it:
Good rebuilder or OEM only. Even a delco alternator I put in died in only 6 months. The alternator heat cycles and causes failure in cheap off brand alternators.

This, big box store rebuilds use the absolute cheapest electronics available.

Check around your area for a good rebuilder. Been going to a local place, quality Bosch parts and lifetime warranty. $75 or for $100 they'll rewind it for higher output ( in case you bring a DSM core ).
 

fastasleep

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Christiansburg, VA
The dealership wants $298.17 including the $20.00 core charge.

NAPA wants $129.00 for a remanufactured one and $189.00 for a Bosch one, which includes the $65.00 core charge. - but you're saying I shouldn't settle for anything less than OEM or a rebuilt OEM?

A rebuild isn't really possible because I don't currently have an OEM alternator to be rebuilt. I think my last two alternators have been from Advance Auto. That is, unless I could find a rebuilt OEM alternator online.

I did find an OEM alternator on www.oemmitsubishiparts.com for $200.00, assuming we use the 75amp alternator. Does anyone know the correct part number?

Thoughts?
 

G

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Feb 24, 2004
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8,896
Location
zompton
Quoting prove_it:
Good rebuilder or OEM only. Even a delco alternator I put in died in only 6 months. The alternator heat cycles and causes failure in cheap off brand alternators.



"even a delco" ? Are you saying you think delco is good?

Guys, this alternator subject has been beat to death here over and over. The final answer is buy a bosch or denso, nothing else. You buy cheap you buy twice.
 

fastasleep

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Christiansburg, VA
Can someone absolutely confirm the correct Bosch alternator part number for our vehicles?
 

tektic

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Dec 19, 2012
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ronkonkoma, ny
MD149750 is the part number for an auto galant Gsx alternator. Does that help? /ubbthreads/images/graemlins/dunno.gif
 

fastasleep

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Jan 14, 2005
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Christiansburg, VA
Nah, I'm able to get the Mitsubishi part number for our Galant VR-4 alternator. The issue I'm having is finding the corresponding Bosch alternator part number for our vehicles.
 

fastasleep

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Jan 14, 2005
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1,779
Location
Christiansburg, VA
Quoting fastasleep:
Can someone absolutely confirm the correct Bosch alternator part number for our vehicles?



Anyone?
 
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