Perhaps if you disconnect the POSITIVE cable from the batteriy(ies) then
short the disconnected cable to the ground cable the CMOS memory in the EMS
will be cleared.  Works for subaru and others.  I don't know much about
Vanagon ecu systems since Detlev Hanschke refused to give me my motor back
after he botched an AUDI transplant.  (Beware this fellow)