Voltage reading problem
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From: London
Voltage reading problem
Well here is post number 3.............. 
When driving my 82 euro the voltage has suddenly started to read up in the red! When idling it's fine (it does flick about a little bit though).
Any ideas?
When driving my 82 euro the voltage has suddenly started to read up in the red! When idling it's fine (it does flick about a little bit though).
Any ideas?
Craic Head
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From: Jersey Shore, USA
Hey James,
I'm sure the experts here will give you more, but off the top of my head I'd say to check and clean all of your ground points. Next thing would be just to verify where the problem is.
Check the voltage at the battery with a VOM and see if it agrees with your guage. If so, you've got a charging problem, if not (and the battery voltage is in an acceptable range from 12-14vdc, then it's your guage).
It looks like you're new here, so you should do some searching through the archives and also read through the thread for new visitors about electrical PM. Go through the whole system to make sure all grounds are clean and all relays and fuses are seated properly and have good clean metal-to-metal contact.
I'm sure the experts here will give you more, but off the top of my head I'd say to check and clean all of your ground points. Next thing would be just to verify where the problem is.
Check the voltage at the battery with a VOM and see if it agrees with your guage. If so, you've got a charging problem, if not (and the battery voltage is in an acceptable range from 12-14vdc, then it's your guage).
It looks like you're new here, so you should do some searching through the archives and also read through the thread for new visitors about electrical PM. Go through the whole system to make sure all grounds are clean and all relays and fuses are seated properly and have good clean metal-to-metal contact.
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From: Nova Scotia
A true high voltage reading when running is a blown regulator or power diode in the alternator. At the battery or underhood jump post, with a DVM/VOM, the battery should read ~12.3 - 12.6V: once confirmed the battery is OK, start the car and read ~13.8 - 14.2V if the alt. is OK.
You can further test the alt. by switching to volts AC ... there should be no significant AC signature to the output if all 6 diodes are OK.
You can further test the alt. by switching to volts AC ... there should be no significant AC signature to the output if all 6 diodes are OK.
Captain Obvious
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From: Cambridge, Ontario, Canada
I had this problem with my first 928 an '83. Sometimes the gage wouls peg out into the red, usually at night, the headlights/dash lights would go extra bright followed by one of them getitng burnt out. It was a failed voltage regulator and the local laternator shop replaced it for ~$20. The regulator is a common part shared by many VW alternators so any shop can fix it.
Nordschleife Master
Joined: Oct 2006
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From: Orange, Cal
This is not something to let go either.
Radio Shack sells a LED thing that plugs into the lighter socket for less than $10, I own 3 of them, loan them out to friends and often leave one plugged into the car all the time. Shows green, yellow, red and gives you an idea of what is wrong, battery, or alt, or nothing. Actually checking the battery etc. I use a meter, but noticing a problem the RS thing works great.
Radio Shack sells a LED thing that plugs into the lighter socket for less than $10, I own 3 of them, loan them out to friends and often leave one plugged into the car all the time. Shows green, yellow, red and gives you an idea of what is wrong, battery, or alt, or nothing. Actually checking the battery etc. I use a meter, but noticing a problem the RS thing works great.
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From: London
I'm thinking along the lines of the alternator. I notice at night that the lights and dash lights are dimmer at idle but brighter when driving.
When ever I've had an alternator problem on cars in the past the electrics have always started doing strange things.
I'm getting it serviced in Feb so I'll get it checked out then.
When ever I've had an alternator problem on cars in the past the electrics have always started doing strange things.
I'm getting it serviced in Feb so I'll get it checked out then.
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7th Gear
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From: 8 MILES FROM MANHATTAN IN NORTH JERSEY
OH ONE MORE THING IF THESE GENTLEMEN ARE SAYING VOLTAGE REGULATOR & ITS ONLY 20 CHANGE THAT FIRST SOUNDS LIKE THEY KNOW FROM EXPERIENCE & IF THAT SOLVES IT GREAT IF IT IS NOT IT CAN'T HURT & THEN YOU KNOW FOR SURE
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From: Boulder Creek, CA
If the voltage needle is reading in the red, you probably need a voltage regulator -- at the moment. If you continue to drive it that way, you may end up needing a lot more -- diodes and/or windings in the alternator, whatever random electronics & bulbs elsewhere in the car decide that after 25 years, running 25%+ overvoltage is too much to bear...
Team Owner
Joined: May 2004
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From: Philly PA
James this could happen, how about a fully exploded battery, it might just take out the rear hatch window, after it sprays battery acid all over the interior, get a meter on the hot post before you do anymore driving , Stan
Racer
Joined: May 2005
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From: South Detroit
Yeah, an overcharged battery will definitely overheat and warm the plates and even if it doesn't explode will cost you a new battery at the very least. I agree with Mrmerlin- do not drive the car if it is indeed running in the voltage red-zone. Unless, of course, it's driving to Pep Boys to buy a new battery!
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From: London
Well today before driving the car since last week I checked the voltage at the battery when running and when not and the multimeter read within the correct ranges. Also there was no voltage reading when switched to AC. I've been driving about today and this evening and had no re-occurance of the voltage indicating in the red. How strange is that?