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Registered
Join Date: May 2008
Posts: 104
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928 volt gage drops to 10 but car runs fine any idea whats going on?
1980 928, volt gage drops to 10 but car runs fine new battery any idea whats going on? I start it up and everything is fine the volts are at 13-14 I drive for about 45 minutes and then all of the sudden the volts start to drop and then its at 10 but theres no volt light on but the info light comes on the center counsel but the car still runs fine with no problems what could be causing this? any help would be great thanks.
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05-23-2008, 04:19 PM
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Network Native
Join Date: Jan 2007
Location: SoCal
Posts: 10,349
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You can't really trust the pod instruments, first thing is to use a real meter and measure the voltage from the battery and the jump post in the front.
Chances are good what you need to do is to clean all the electrical connections and ground points. I'll add a link to this thread on how to do it later when I find it. Here it is. http://forums.pelicanparts.com/porsche-928-technical-forum/408953-has-anyone-added-more-grounds-where.html#post3938987 Last edited by Danglerb; 05-23-2008 at 07:21 PM.. |
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05-23-2008, 07:18 PM
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Registered
Join Date: Nov 2007
Posts: 54
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If it is just the gauge, (as they are all off) My 1982 has a POT adjustmet on the back of the cluster. Still this adjustment got the gauge to read 12v at idle when system voltage was really 13.5.
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05-23-2008, 07:23 PM
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Registered
Join Date: Apr 2007
Location: LA County
Posts: 53
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Had same issue: An aftermarket volt gauge will fit into the hole for your analogue clock, and it wires easily to the under-hood positive terminal.
Of course, it might be more than a bad gauge. I ignored my mis-reading gauge for about a year, checking every so often with a meter across the battery, until one day the gauge turned out to be reading low correctly, and then I was stuck with a dead alternator and battery. Moral of the story, get an aftermarket gauge asap. |
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05-26-2008, 04:18 PM
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Registered
Join Date: Sep 2007
Location: Fremont, CA
Posts: 160
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I had a simular issue on my 82. I replaced the well worn belt and the cooling hose. Problem solved the reading went up. I suggest checking the simple stuff, is the belt tight? Is the cooling ducting on?
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99 Boxster 5-speed 12 Acura TSX 6-speed |
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05-26-2008, 08:08 PM
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928-Electrics Guy
Join Date: Jun 2007
Location: Phoenix AZ
Posts: 715
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I suspect your alternator/regulator is cutting out as it heats up... does your charge light come on during bulb test? I'd have the alternator tested and meanwhile when its out test the charge light - just ground the small wire that feeds the alternator exciter circuit and see if the dash light comes on with ignition on (you will have to bolt together the 2 connections that normally go to the large alternator connection to make this test work.
The car will run fine on the battery alone - for a little while... anywhere from about 20 minutes to a few hours depending on equipment in operation... cooling fans, heated windshield, blower, lights, headlights, big audio will kill the battery fast... Check it out before you get stranded Alan
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1994 928 GTS Black/Black Manual |
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05-27-2008, 07:26 AM
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