I have a mobile phone handsfree which plugs into the lighter socket, to
provide phone charging and speakerphone.
This works fine in my other vehicles, but in my vanagon this causes the
flasher relay to buzz (not the normal click) and the oil pressure light
to flicker when the ignition is on.
The socket is always live, and the handsfree works fine, causing no
problem with the ignition off, but not with the ignition on or the motor
running.
The relay and oil pressure light are fine without the handsfree plugged
in -- what is happening to cause this?

Bob Turnbull

91 Syncro