Nobody seems  to be able to make a pressure switch that lasts! I had the
same trouble with my MGB, and finally converted it to a manual switch
after going through three pressure switches in six months.

The Vanagon has two of  these, and both must close to send  current to
the lights.  Use an ohmmeter to test them both.  It is entirely possible
that the new one is bad too, my last master cylinder's switches were bad
right out of the box.

Check your brake lights often, I seem to be replacing these switches
about once a year.
--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)

Personal mechanic for:
'70 MGB GT (Daughter's)

Assisting on Restoration (and spending OPM):
'72 MGB GT (Was daughter's, now son's)
'64 MGB (Son's)

Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT