Date: Wed, 17 Jun 2009 20:07:16 -0400
Reply-To: Rick Foster <redhawkf@PEOPLEPC.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Rick Foster <redhawkf@PEOPLEPC.COM>
Subject: Re: Help with Dometic 12v wiring
Content-Type: text/plain; charset=UTF-8
Thanx Mark, Neil and Dennis! With your great help I found my problem. To re-cap: My Dometic had not worked in years. With the help of this list and Frak Condelli's web page I removed and refurbished and thoroughly bench tested the fridg and all worked well. I was testing the 12v connections under the drivers seat and I couldn't get any power. After checking continuity of all wires, Alt led working I checked the relay and IT was not working! Went to my FLAPS who did not have an exact replacement but did have a 87-87a 30amp relay($2.99). A 50 cent 2spade T connector allowed me to make the two 87 terminal connections, started the engine, alt led off and viola! Power! Now to reinstall the dometic and finish a few other things. Thanx again guys!!
Rick Foster
85 Westy
>>
>>
>>
>>
>
>
>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 r=
>elay.
>
>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.
>
>>
>------------------------------
>
>Date: Tue, 16 Jun 2009 05:45:21 -0400
>From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
>Subject: Re: Help with Dometic 12v wiring
>
>You won't see real voltage there until the alternator is "kicked" in, =
>(ignition on and light off). The concept of using the blue wire is that =
>if the alternator should fail the fridge will turn off.=20
>
>Dennis
>
>
>-----Original Message-----
>From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf =
>Of Rick Foster
>Sent: Tuesday, June 16, 2009 12:07 AM
>To: vanagon@GERRY.VANAGON.COM
>Subject: Re: Help with Dometic 12v wiring
>
>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.
>
> -? my relay is fried? It is VW # 411915511B.
>
> - ? GW has a 'second battery relay' that has the same spade #'s; is =
>this the same relay?
>
> - ? Do I need a new Alt?
>
> - ? 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
>
>
>
>
>
>
>
>
>>Sent: Tuesday, June 09, 2009 3:48 PM
>>Subject: Re: Help with 12v Dometic wiring
>>
>>
>>> No, the wire that seems to come from the ignition switch is really a
>>> ground wire of sorts, through the starter motor coil. The voltage =
>that
>>> triggers the relay comes in on the blue wire, from the alternator. If
>>> you have something other than a Bosch alternator the blue wire may =
>not
>>> work anymore.
>>>
>>> Mark
>>>
>>>>
>>>>
>>>> Now I'm stumped and stymied with getting back on the road with my
>>>> Dometic working. It never has, but with help of Lorean and Ken, I =
>took
>>>> it out, refurbished it, bench tested each system and it worked. =
>Before
>>>> putting it in, I tested the 12v input and here's what I've got:
>>>>
>>>> 1- no auxillary battery, just stock wiring to'refrigerator heater
>>>> relay'(bently 97.32.e), plan to put in aux bat in future.
>>>>
>>>> 2- clean wiring from relay thru fuse block and to ignition switch.
>>>>
>>>> 3- + Power from bat at term 87 thru term 30 to frig connection.
>>>>
>>>> 4- continuity in blue wire from term 87 to D connection at the
>>>> alternator.
>>>>
>>>> 5- No Power at term 85 from the ignition switch but + continuity =
>thru
>>>> this wire to the ingnition terminal (term 50). This term is coupled =
>with
>>>> a #10 wire that goes I know not where. Bently (97.62) looks like =
>it's
>>>> track 78, but it looks like it goes off where 'no man has been =
>before'! I
>>>> can't read any 'track 78' anything functional and I'm not spark =
>engineer.
>>>> Spock where you!
>
>>Date: Tue, 16 Jun 2009 06:13:25 -0700
>From: mark drillock <mdrillock@COX.NET>
>Subject: Re: Help with Dometic 12v wiring
>
>You need to make sure the alternator part of the circuit is working
>correctly first, then connect the relay to it.
>
>With the blue wire not connected to the relay, make sure the dash alt
>led comes on when the key is turned on and then goes out when the engine
>is running.
>
>If the alt led behaves as it should, connect the blue wire back to the
>relay, pin 86. Pin 85 should be connected to ground. With the engine
>running and the alt led off, touching the blue wire to pin 86 of the
>relay should make the relay click, every time. If not, the ground is
>missing from pin 85 or the relay may be bad, or the blue wire is not
>connected to the alt led circuit anymore.
>
>You must verify that the dash alt led is behaving as it should since
>that signal is what controls the relay. Then the blue wire should
>provide +12v to the pin 86 of the relay.
>
>Mark
>
>
>
>>>> Sent: Tuesday, June 09, 2009 3:48 PM
>>> Subject: Re: Help with 12v Dometic wiring
>>>
>>>
>>>> No, the wire that seems to come from the ignition switch is really a
>>>> ground wire of sorts, through the starter motor coil. The voltage that
>>>> triggers the relay comes in on the blue wire, from the alternator. If
>>>> you have something other than a Bosch alternator the blue wire may not
>>>> work anymore.
>>>>
>>>> Mark
>>>>
>>>>
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