Date: Mon, 15 Jun 2009 22:37:41 -0700
Reply-To: neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: neil N <musomuso@GMAIL.COM>
Subject: Re: Help with Dometic 12v wiring
In-Reply-To: <22121281.1245125239143.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>
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On Mon, Jun 15, 2009 at 9:07 PM, Rick Foster<redhawkf@peoplepc.com> wrote:
> Being new to posting on this list and my computer doing funky things at times I know not if at times my follow-up post's didn't make it here, I've been waiting for replies, so I venture again: (thanx Craig, robert, Mark and Scott)
>
> This thread took the direction of 'The Incredible Journey' thru my relay. Facinating, and possibly why my relay is fried, the input wiring (thanx Robert) was wrong. I'm still stumped about how to know my house wiring is OK before installing the Dometic!
>
> - I checked output at my Alt blue wire spade while running and got 0.12v. My alt lite goes on when I turn ign on but get no voltage from the relay at that spade on the relay.
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> -? my relay is fried? It is VW # 411915511B.
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> - ? GW has a 'second battery relay' that has the same spade #'s; is this the same relay?
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> - ? Do I need a new Alt?
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> - ? Should I get a 'aux bat wiring kit'?
>
> Thanx, and count me in too!
>
> (Freebo, Dometic Harmony is the Goal!)
>
> Rick Foster
> '85 Westy, 2.1
> So. OR
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Is there a ground connection to 86 of relay in question?
How many batteries do you have installed?
Likely you know this, but a relay is basically a switch.
If VW # 411915511B is the "fridge" relay, assuming fridge turned on to
12V setting, relay does this:
engine running: relay energized (internal switch closed), power
allowed to flow from alternator to Dometic. Engine off, relay NOT
energized, (internal switch open) battery Dometic connected to doesn't
get drained. Bear in mind that power from alt basically goes to
starter battery, then from + post of this battery, to 30 buss which
I'm pretty sure Dometic is connected to. (check Bentley.... mine
outside)
2nd battery relay (aka isolator relay). Works same way as above.
If a 2nd battery (aka "aux." or "house") is installed, it is
connected, via an isolator relay to the + post of your starter
battery. Wired correctly, when engine off, relay isolates, or
disconnects the aux. battery from starter battery. That way any loads
wired to aux. battery, will only draw power from it. (and when
cranking engine, power only comes from starter battery) When engine
running, relay energizes via the blue wire, making connection between
starter and aux. batteries to allow power to flow from alternator to
charge it.
Diagram
http://www.keithandsylvia.co.uk/tech%20pages/splitcharge.htm
note the text on fuses. "split charge" relay means same thing as isolator relay.
Both relays behave the same way and do similar jobs.
To test either one:
Disconnect wires from 30 and 87 of relay. Make sure a ground is
connected to 86 and that blue alt wire connected to 85. Check for
continuity between 30 and 87. There shouldn't be any. Fire up your
engine. Check for continuity again. There should be continuity between
30 and 87. If there is, the relay is working.
Thought this page shows relays with the 87a pin, the theories are the same.
http://www.bcae1.com/relays.htm
Hope that helps
Neil.
--
Neil Nicholson '81 VanaJetta 2.0 "Jaco"
http://tubaneil.googlepages.com/
http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines
