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| − | David Bierl:
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| − | In understanding Vanagon (or any other) wiring diagrams there is a
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| − | not-so-little trick that will make it vastly easier to figure out
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| − | what's really going on in a circuit. Before you can do this of
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| − | course you have to be familiar with Bentley 97.3-97.6. so the
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| − | diagrams make any sense at all.
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| − | The trick is this: First copy the page in question so you won't
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| − | wreck the original if you mess up somewhere. Get yourself an
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| − | assortment of colored pencils, at least five or six including brown
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| − | and red. Then take a look at
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| − | http://picasaweb.google.com/dbeierl/FiguringOutVanagonWiringDiagrams#
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| − | for a working example of how it's done. You may want to keep it open
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| − | to refer to or make a color print of it to use the first time or two
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| − | you do this.
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| − | Start by locating the grounds. Since this is a physical schematic
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| − | some of them may originate far away from where you're looking even if
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| − | it would be easier to understand if they simply drew all of them
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| − | straight down to line at the bottom line of the page, which is
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| − | chassis ground. Every terminal labeled as 31 is a ground. Every
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| − | ground you find, draw a brown line next to the wiring for its whole
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| − | length. For switched grounds I recommend a dashed line instead of
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| − | solid upstream of the switch.
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| − | Then look for the +12 supply wires and color them red. You may well
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| − | want to use different colors for unswitched (terminal 30), switched
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| − | by ignition (terminal 15), and switched by the load reduction relay
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| − | (X-terminal on ignition switch operates it; power upstream is 30 at
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| − | the relay, downstream (switched) is 87 like all relay
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| − | outputs. Again, power that's switched downstream should use a dashed
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| − | line downstream of the switch.
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| − | Now pick a wire and figure out what it does. Follow it off the page
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| − | if necessary and label where it goes on your drawing. If you can't
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| − | figure it out, pick another wire. As soon as you know what it does,
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| − | label it as such then pick a color for it and draw solid or dashed
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| − | line as appropriate. If a single wire does multiple things, as in
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| − | the circuit from 53e at the motor up to the switch, down to the relay
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| − | and thence to the motor 53 terminal, use multiple solid or dashed
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| − | lines as appropriate (Note: the pink wire should be dotted for its
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| − | entire length and there should also be a brown dotted line for the
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| − | whole length of that circuit. Can you discover why? Answers on
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| − | request. Hint: I missed one of the functions of the auto-park switch).
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| − | Keep on doing this for wire after wire until you understand them all
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| − | (or are certain you understand enough of them, which may or may not
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| − | be true). Each wire you figure out makes the rest easier, and the
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| − | colored lines take away the visual anonymity of Joe Random
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| − | Black-line-on-the-page. Now you can follow the circuit around and
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| − | find out where a particular problem might (or must) lie as well as
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| − | where it cannot.
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| − | This is the second time I figured out this particular wiper
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| − | circuit. The first time I forgot this trick I learned thirty years
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| − | ago, and it took me over an hour. This time I remembered, and it
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| − | took about ten minutes after I found the colored pencils and
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| − | photographed the page. And I was easily (but not in ten minutes)
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| − | able to establish that the relay cannot possibly be correct as drawn
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| − | (since at some point it would hook +12 directly to ground) and how it
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| − | would actually have to be (which happens to coincide with the diagram
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| − | molded into the side of the actual 19 relay, but I didn't know that
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| − | at the time. I definitely did *not* figure that part out the other time.
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| − | Yours,
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| − | David
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| − | Robert Keezer adds:
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| − | This is an idea I had 15 years ago when I was installing Digifant 2 and later Motronic fuel injection wiring in my 82 Westfalia ,with one additional trick-
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| − | make the copies larger than the Bentley, making them easier to read.
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| − | The circuit tracks are very close on top of the page, and I mixed up the 1 wire with the 15 wire and fried the computer before I ever got it started.
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| − | Colored marking pens also work well. Once you learn these diagrams, you can troubleshoot any circuit easily, or do a conversion. Many of the color codes for Vanagon are the same for Jetta , Golf etc.
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| − | [[Category:diagnostic_tips]][[category:understanding_bentley]]
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