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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHAlternator or voltage regulator?
Reported repair
Replace alternator and the issue is
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Reported fix · Original poster
Just as an update, changed the alternator and the issue is solved.
Leading evidence: 'Replace alternator and the issue is' (1 discussions report resolution; 0 report an unsuccessful attempt). Across 1 matching discussions, the most frequently mentioned possible cause is 'high rpm issue as well' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Replace alternator and the issue is' (1 discussions). For that action, 1 discussions report a resolution and 0 report an unsuccessful attempt. The most frequently reported fix is 'Replace alternator and the issue is', supported by resolution reports in 1 discussions. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
The alternator was replaced by previous owner so I assumed it was the regulator.
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Performed · outcome unconfirmed · Original poster
I went to the mechanic and he tested the battery and said it's fine.
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Performed · outcome unconfirmed
I use a big "hat pin" with a wire attached to my DVOM, just pierce the big 12v wire near the alternator..
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Suggestion
Like I said, as with most automotive diagnostics, it is a process with multiple steps that when followed each step can change directions of the next step or test, so it is incredibly hard to keep up with in an all inclusive text discription.
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Suggestion
But like I said, the first thing to do is test the charging voltage "at the alternator".......The test results can lead in two different directions ....( and each test afterwards) ..
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Suggestion
The only true way to test the alternator is an Ossciliscope to see if a diode is shorted ,ect.....Then if the Scope pattern is OK and the charging voltage "at the alternator is low" then the regulator is bad...
Test charging voltage "at the alternator".......the
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Suggestion
But like I said, the first thing to do is test the charging voltage "at the alternator".......The test results can lead in two different directions ....( and each test afterwards) ..
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Rennlist: 1 discussions
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Hi all!
Quick one today. I went for a drive the other day on the track and at high RPM the error message "WARNING BATTERY / GENERATOR". So here are the facts;
I drove for 200 miles since and all good
Whilst driving voltage on the dash reads 13.5V-13.7V
I went to the mechanic and he tested the battery and said it's fine.
Same mechanic measured voltage on idle with lights on and it was around 11.5-12V, he said change the regulator / alternator.
Went to another mechanic, he said as you have driven 200 miles, the alternator must be working thus change regulator.
As i drive every 40 miles or so I get a error ping message.
Is it the regulator or alternator ?
Thanks!
The voltage regulator is part of the alternator. You can just replace the regulator but you have to pull the alternator to get to it. Given the age of our cars, I would just buy a new alternator. Don't go rebuilt on this one. You can get a new alternator on Amazon.
Disagree, If it is a $32 part why spend ten times that? My regulator failed 2 years ago. Luckily have another car with the same alternator so I was able to test it.
If you don't want remanufactured I believe the dealer is the only option and those are $1800
Edit: Looks like there are some new ones on Amazon from manufacturers I've never heard of.
I get that, but if time is money, then a new alternator with regulator is possibly a good choice, especially if they are paying someone else to do it. Some of these cars are 1/4-century old now (mine)
You ( or your Tech) really needs to test charging voltage " at the alternator" not up at the front of the car.... The "Y" cable can seriously effect the charging voltage and is a very common problem....
The only true way to test the alternator is an Ossciliscope to see if a diode is shorted ,ect.....Then if the Scope pattern is OK and the charging voltage "at the alternator is low" then the regulator is bad...
The diagnostics is a process that must be followed correctly, or shoot the parts cannon...
Thanks for the reply. My tech is an awesome person, but there is a reason I come to rennlist :-). Anyways I am comfortable working on my cars (have a lift and did the water pump / thermostat / coils / mounts / belt / pulleys service a couple weeks back).
Anyways a reconditioned BOSCH unit costs here 200 bucks given I return the old alternator. I have a multimeter, however when it comes to electricity / electronics. I am a complete newbie, could you please in detail describe what I need to do ?
Thanks!
Like I said, as with most automotive diagnostics, it is a process with multiple steps that when followed each step can change directions of the next step or test, so it is incredibly hard to keep up with in an all inclusive text discription.
Due to the next step depends on the outcome of the previous test results....
Example of Fault tree diagnostics...
But like I said, the first thing to do is test the charging voltage "at the alternator".......The test results can lead in two different directions ....( and each test afterwards) .. and is why some people shoot the parts cannon.......
.
I am all for testing and fault finding...to a reasonable extent. However, in this case we are working with +20 year old cars, and alternators are expendable, windings, bearings, diodes, regulator. I would never go with a rebuild for cost savings. Did that once with a starter (thought how clever to save a bit) and it busted within a year. What a PITA. Given that the alternator is so integral to the function of the engine/car, do it once and do it right. Then move on. If you own a +20 year old Porsche 996 and balk at $350...well...then...I have no words.
Amazon
Amazon
Amazon
One alternative is to take the alternator to a shop and have them test it. Not a place that just tests the voltage output either, but a place that can really test it.
PorscheTech3 is saying that you need an oscilloscope to view the actual waveform coming from the alternator to determine if the regulator is bad. It isn't enough to put a voltmeter on it. And to test the voltage coming from the alternator, you have to access the back of it while running. He is suggesting you connect the positive side of your oscilloscope to a pin and use that to pierce the cable connected to the back of the alternator. A new rebuilt alternator would be less expensive than buying an oscilloscope. If it is the original alternator, I would just replace it. It will be the last time you do.
I always find it strange when people try to shame people for not spending money they may not need to. Like they don�t deserve to own a Porsche.
Whatever.
The one you listed is for 2004 and newer cars.
Maybe all is perfectly fine..... you said you were on the track... and at high rpms. depending on the system it could actually put out a bit to high of voltage at super high rpms and then you would get the flag/warning. Also I've read a few times about reducing or enlarging pully sizes for track use or extra cooling and such alternative. Just saying if you go 200 miles and all is fine, and car is starting no more odd flags it could be something like this happened.
Just my 2 cents. I recently went through a bizarro voltage spike on my 1999 sending it into panic mode. The alternator was replaced by previous owner so I assumed it was the regulator. I swapped it out but the issue continued. I got a lot of feedback from members on testing V at battery, at alternator etc etc. Nothing really added up. In end I replaced the alternator with a brand new one for the 997 and never had a problem again.
Amazingly this has gone down in price $50 since I bought it seven months ago. Its brand new and you don't have to send back your current one.
Amazon
Amazon
My issue was a high rpm issue as well.
https://rennlist.com/forums/996-foru...imit-revs.html
Not sure if you have same issue, but just passing along.
Hi All,
Just as an update, changed the alternator and the issue is solved. After I pulled the old one out I came to the conclusion, not worth the hassle with a second instal and the old alternator was super corroded.
Thanks for a ll the help! !!
