If the computer is bad, will the VR voltage spike (to say, 18.5 V)?
01-05-2009, 05:34 PM
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Does the ECU/computer control Voltage Regulator's Voltage Output?
...So if @ 4,000 rpm the car outputs 18.5 V it might not necessarily be a bad VR-- it could be a bad ECU/computer?
IS the ECU the main computer for the car? And is there a fuse for it?
--2001 s4 avant.---
IS the ECU the main computer for the car? And is there a fuse for it?
--2001 s4 avant.---
01-05-2009, 05:47 PM
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the ECM networks all of your cars
components, brake inputs/outputs, engine management etc with pre-set amounts. So yes it does control your VR but only with what it knows to. So if one of your VR's is damaged its going to keep asking it to get it the value it wants to "hear". I know theyre expensive to replace, but if but if you have some free time here is a way to test them. Check back in 5 mins
01-05-2009, 05:47 PM
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ECU has an internal 5V regulator, input is 12V +/- ...
If you are getting a voltage spike out of the alternator, then its the voltage reg IN the alternator itself.
Seen this many times and every time a NEW alternator fixed the problem.
Good Luck
Seen this many times and every time a NEW alternator fixed the problem.
Good Luck
01-05-2009, 05:56 PM
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I didn't know there were 2 VR's, one inside and one out of the Alternator...
Not only is the voltage spiking, but warning lights are on, tranny in fail-safe mode in driveway, and battery light comes on @ 3300 & gauges malfunction. Got me thinking, if the ECU is not working right, then the Voltage Regulator isn't being regulated, therefore the 18.5V @4,000 rpm. ????????
Was going to simply replace the VR ($49) until you told me it's the one inside the alt...now I don't know what to do.
-->excitedly waiting for Skribbs info----->
Was going to simply replace the VR ($49) until you told me it's the one inside the alt...now I don't know what to do.
-->excitedly waiting for Skribbs info----->
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01-05-2009, 06:02 PM
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my mistake, I shouldve said Voltage regulator AND rectifier
its a diode tree basically. I bet one or more is burnt up. you can have your alternator rebuilt or just buy a new one like Mark said. But I would limit our driving so you dont get stuck somewhere.
heres what it looks like inside your alternator. the VR is on the left, the rectifier on the right. Both are rather easy to remove and replace. But its your call. I drive a 13 yr old 12v so.. I just replaced mine.<ul><li><a href="http://www.alternatorparts.com/DCP_0620a.jpg">heres</a></li></ul>
heres what it looks like inside your alternator. the VR is on the left, the rectifier on the right. Both are rather easy to remove and replace. But its your call. I drive a 13 yr old 12v so.. I just replaced mine.<ul><li><a href="http://www.alternatorparts.com/DCP_0620a.jpg">heres</a></li></ul>