OK, so the Bentley shows the fridge relay for the Westy as being "tripped"
by the alternator wire and a connection to terminal 50 (start position) of
the start switch. Presumably this keeps the relay off during starting of the
van.

My 1982 diesel had a factory looking blue wire (appears to be from the
alternator) and then the other side of the coil for the relay was grounded
on the screw that held the relay. This would also be off during starting of
the van, but would connect the batteries if the key is in the "on" position,
correct?

I thought it would be better to go with terminal 50 since that won't
activate the relay until the alternator is charging (that is how my 83
waterboxer worked--I could hear the relay as I revved the engine and saw the
headlights brighten), and I hooked up a second relay (no need to debate the
relay/isolator--that's not what the question is about) to charge a second
battery. I brought a wire from terminal 50 on the emergency brake light
switch back under the seat to the relay. Now the original relay runs the
fridge and the second relay. The second relay allows the second battery to
be charged once they both kick in.

Problem: The relay(s) chatters at low rpm and when the brake lights come on,
especially when the van is still warming up. Other factors that might be
related. The alternator light won't turn off, but I know it is charging
because I can watch the voltage change (digital VOM) on various hot wires
and I can see the change in voltage from approximately 12.5-12.7 up to
13.6-13.7 volts or so. I can hear the relay kick in as the engine revs so I
am guessing the alternator light problems is after the "T" for the fridge
relay. But, maybe its related. Anyway, it kicks in as I rev the engine, it
just doesn't want to stay. Both the fridge relay and the second battery
relay are using the single pretty small (20-22 gauge?) wire coming from
terminal 50--could the wire be too small? BTW, I seem to recall a charging
alternator was supposed to be around 14.2 volts, or am I going to be lower
from running the glow plugs?

Anyone know why the diesel was done differently or what would cause this
chatter?

Thanks for any help.

Myron Lind
1982 Westy TDD/5 speed (WOW, the true hydro motor mount made a HUGE
difference in engine noise)
Harrisonburg, VA