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Rennch on YouTube
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Could a bad alternator cause gauges to stop working?
Just wondering if that could be the reason for my car's flakiness..
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Michael O'Neal - 69 RSR Clone(ish) - The build: http://bit.ly/69porschersr 69 911S Blasphemy Build on YouTube Rennch Youtube Channel: http://rennch.com/Youtube Instagram: https://www.instagram.com/_rennch_/ |
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05-28-2010, 10:33 AM
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Hi
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In all my years I've never heard of that.
I do know that these cars are very finicky when it comes to grounds.
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"A good sense of humor is the best thing to have in your toolbox when working on these cars." Quote by Charles Freeborn, Pelican. |
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05-28-2010, 10:37 AM
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Rennch on YouTube
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Ok...thanks. The mystery continues.
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Michael O'Neal - 69 RSR Clone(ish) - The build: http://bit.ly/69porschersr 69 911S Blasphemy Build on YouTube Rennch Youtube Channel: http://rennch.com/Youtube Instagram: https://www.instagram.com/_rennch_/ |
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05-28-2010, 10:43 AM
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Join Date: Oct 2008
Location: Denver, CO
Posts: 3,494
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a bad voltage regulator fried my tach (and my dme) on my '86 carrera. North Hollywood Speedometer fixed my tach for me and I was able to get my dme re-soldiered.
So, yes, it can happen, especially if the alternator's voltage regulator is failing and spiking high voltage through the electrical system. |
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05-28-2010, 10:44 AM
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Rennch on YouTube
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Its not just my tach...all my gauges aren't working at the moment. They are spiking. Meaning, I turn the car on, and they pin out. My tach was weird...I was on a drive, and it became intermittent...then stopped working entirely.
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Michael O'Neal - 69 RSR Clone(ish) - The build: http://bit.ly/69porschersr 69 911S Blasphemy Build on YouTube Rennch Youtube Channel: http://rennch.com/Youtube Instagram: https://www.instagram.com/_rennch_/ |
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05-28-2010, 10:47 AM
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Location: Denver, CO
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What's your car's voltage when the engine's running. A bad voltage regulator will cause it to fluctuate into the high teens, which can fry stuff that's expecting low teen voltages. Your description sounds more to me like a grounding issue
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05-28-2010, 10:53 AM
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Rennch on YouTube
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My voltage running is around 11.8, which led us to believe the alternator wasn't doing anything.
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Michael O'Neal - 69 RSR Clone(ish) - The build: http://bit.ly/69porschersr 69 911S Blasphemy Build on YouTube Rennch Youtube Channel: http://rennch.com/Youtube Instagram: https://www.instagram.com/_rennch_/ |
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05-28-2010, 10:56 AM
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11.8 VDC with engine running? you've your answer right there. Glad it's not an overvoltage condition.
Best, Doyle
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Recording Engineer, Administrator and Entrepeneur Designer of Fine Studios, Tube Amplifier Guru 1989 Porsche 911 Carrera Coupe 25th Anniversary Special Edition Middle Georgia |
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05-28-2010, 01:10 PM
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Rennch on YouTube
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Which brings me back to the original question...could that cause gauge weirdness?
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Michael O'Neal - 69 RSR Clone(ish) - The build: http://bit.ly/69porschersr 69 911S Blasphemy Build on YouTube Rennch Youtube Channel: http://rennch.com/Youtube Instagram: https://www.instagram.com/_rennch_/ |
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05-28-2010, 01:18 PM
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Location: Mexico
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Check the grounds, probably the instruments have a common ground which must be disconnected.
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05-28-2010, 01:41 PM
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Rennch on YouTube
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Checked those, all fuses, and have done a ground test on the gauges. All checks out...
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Michael O'Neal - 69 RSR Clone(ish) - The build: http://bit.ly/69porschersr 69 911S Blasphemy Build on YouTube Rennch Youtube Channel: http://rennch.com/Youtube Instagram: https://www.instagram.com/_rennch_/ |
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05-28-2010, 02:24 PM
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As Doyle said either your alt. or regulator is bad.
Should have around 12.8 volts or so running. Don't know if this will fix your guages but i'd fix this first.
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Pete 79 911SC RoW "Tornadoes come out of frikkin nowhere. One minute everything is all sunshine and puppies the next thing you know you've got flying cows".- Stomachmonkey |
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05-28-2010, 05:44 PM
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Michael,
You should have 13.5-14.5 V when the engine is running. 11.8 is too low with the engine OFF. Your voltage regulator is toast. I'll bet fixing that fixes everything. I had a bad alternator and gauges were spooky, the wipers turned on by themselves, etc. I don't know the extent of your electrical changes (you have a '69 with a 3.0 CIS, right?) I'm guessing you have the new VR that's integral with the alternator, behind the fan. Your 69 would have originally had a separate VR on the left firewall by the CD ignition. |
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05-28-2010, 06:00 PM
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Gretchen
1979 Porsche 911SC
