My 82 Westfalia did'nt have a fridge relay and the  battery went flat several times until I found out about the relay and installed one. 
Wired the ground to the frame. Works like it should, 14 years now. 
I never heard about the starter solenoid used as ground til now. 

Robert
1982 Westfalia

--- On Tue, 6/9/09, mark drillock <mdrillock@COX.NET> wrote:

> From: mark drillock <mdrillock@COX.NET>
> Subject: Re: Help with 12v Dometic wiring
> To: vanagon@GERRY.VANAGON.COM
> Date: Tuesday, June 9, 2009, 7:15 PM
> Yes, that is right. The starter
> solenoid coil is the ground for the
> fridge relay and if the red/black wire is pulled off the
> starter the
> fridge relay won't work even with the engine running, since
> it won't
> have a ground anymore.
> 
> Not all years used the starter as the ground for the fridge
> relay so of
> course the ones that don't will still work with the
> red/black wire
> pulled from the starter. The fridge relays that use the
> starter as
> ground have a small red/black wire attached to relay pin 85
> or 86.
> AFAIK, all the aux battery relays used the red/black to the
> starter as
> ground.
> 
> Mark
> 
> Scott Daniel - Turbovans wrote:
> > well that last scenario sounds nasty.
> >
> > ok, tell me this ..........
> > if the starter trigger wire fell off the solenoid ,
> > and you roll started the van ......and� the
> engine fired� and the alt.
> > started charging,
> > would the fridge relay then not be able to energize ?
> > ( due to lack of esoteric connection to the fridge
> relay from the starter )
> > Scott
> >
> > ----- Original Message ----- From: "mark drillock"
> <mdrillock@COX.NET>
> > To: <vanagon@GERRY.VANAGON.COM>
> > Sent: Tuesday, June 09, 2009 6:36 PM
> > Subject: Re: Help with 12v Dometic wiring
> >
> >
> >> I'm right in this case. The ignition key switch
> does nothing to the
> >> circuit except when in the far start position it
> puts 12 volts on the
> >> relay "ground" while cranking. This keeps the
> relay from activating
> >> during starting. Some years use this "ground" for
> the fridge relay and
> >> some don't. This is a redundant feature since the
> blue wire won't
> >> trigger the relay anyway until the engine starts
> and the alt light
> >> goes out.
> >>...................................
>