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trying to put ammeter on vanagon
by
motomike33y
on 05 Feb, 2012 18:23
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trying to put ammeter on my vanagon diesel. 1982 w/stock alternator. checked voltage from blue wire coming out and it was 12+ so used it to positive pole and ground to negative. hooked up and battery light came on on dash, ammeter showed -30 volts. obviously a problem somewhere. now light won't go off on dash-should when throttle blips and alternator switches on. 12+volt still coming out of red wire but nothing from blue wire. I assume that I did something to the voltage regulator but looking for explanations as to what. multimeter showed voltage ok from wire and ground but somehow different when hooked up to ammeter?
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#1
by
fatmobile
on 05 Feb, 2012 20:02
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Question is too choppy for me to understand.
checked voltage from blue wire coming out and it was 12+ so used it to positive pole and ground to negative
Blue wire where, positive pole where,... because the alternator doesn't have a neg pole does it?
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#2
by
ORCoaster
on 05 Feb, 2012 21:05
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Well if you were trying to install an ammeter that is not the way to do it. You run the gauge between the wire that goes from the alternator to the positive side of the battery. Has to be kind of stout, to handle the +or - of 60 amps or so.
You can also run it between the battery and the main fuse box.
What ever you did running it between the blue wire and the positive of the ammeter seems to have messed up the exciter. Good luck on figuring that one out.
Anyone do this and have the fix for it?
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#3
by
motomike33y
on 06 Feb, 2012 05:54
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thanks-the blue wire is one that comes from the alternator-along with the red that goes to the battery. On my 91 jetta I had hooked the ammeter to the blue wire that came from the alternator so I thought I could do the same, after checking with my multimeter to verify voltage coming from it. I'll have to pull the regulator off one of my other vanagon alternators to try correcting the problem and then I'll hook my wire to the red one. I'm puzzled by what happened though so if anyone has explanation I would appreciate it
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#4
by
motomike33y
on 06 Feb, 2012 07:16
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it appears that I still have 12+ voltage going from the alterntor to the battery via the red wire but the exciter isn't working so the battery light stays on. I'm confused after reading more about the exciter circuit in that voltage may go to it until it excites then the 12+ voltage flows from the alternator thru the blue wire. That could help explain the conflicting readings on my multimeter and ammeter
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#5
by
Luckypabst
on 06 Feb, 2012 07:51
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An ammeter needs to see the full electrical load pass through it (except for the starting circuit) for it to tell you anything. To do this, you would need to install it inline with the lead feeding the fuse panel, not that blue wire. The alternator exciter circuit also provides minimal amps... enough to trigger the small relay in a Westfalia but not enough to switch a larger Ford style battery relay.
Chris
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#6
by
ORCoaster
on 06 Feb, 2012 08:16
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Blue wire would be better suited to hook in a volt gauge not the amps gauge. Like he says go through the line feeding the main fuse panel to all the electrical circuits.
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#7
by
motomike33y
on 06 Feb, 2012 09:36
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yeah, I did some more research and a voltmeter is what I really want, but I had some ammeters laying around so thought I'd use one but didn't realize the difference in wiring circuit needs
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#8
by
motomike33y
on 08 Feb, 2012 05:56
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swapped alternators and that took care of the alternator light problem, now I have a volt gauge on the way from ebay, and will look to another way of hooking it up. I'm going to see if the voltage regulator failed on the removed alternator since I have several 65 amp alternators from rabbit/jetta/vanagons
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#9
by
ORCoaster
on 08 Feb, 2012 06:28
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Just wire it from ground through the gauge and to a positive wire taken off the ignition.
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#10
by
motomike33y
on 08 Feb, 2012 06:42
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yeah, that will then let me use one of my wires to hook up temp gauge(I've got an insulated 3 wire strand running from the engine compartment up into my dash for hooking up gauges and relayed glow-plug switch)