As for the 91 fridge relay needing the DRL relay to be present there is
a clue you can almost dig out of the Bentley DRL wiring diagrams. The
fridge relay blue wire is normally plugged into pin G4 of the main relay
panel as shown in the camper wiring sections.

But, the 89/90 and 90/91 versions of the DRL both use pin G4 themselves.
So page 200.239 shows a blue wire expansion connector available from G4
as part of the DRL harness for 89/90 DRL version.

This changed for 90/91 DRL and instead there is an extra blue wire
expansion coming from the output of the DRL relay for the tail lights,
shown on page 97.242 current track 5.

This seems an odd change by VW but there must have been a reason.

Mark

Steve Williams wrote:

>.......
>
> The bizarre thing is that on 97.33b, there is absolutely no indication
> (that I can find) that the blue wire coming from the alternator runs
> through a relay on the way to "Refridgerator 12 bolt heater relay".�  My
> clue was the T2a/2 connector which I found behind the fuse panel and
> followed to where there should have been a relay plugged in.�  I think
> there's probably a later supplement for a 1991 camper... or not!�  lol
>