Fitting a roof aerial

[maxp]

Ever since ive had the car, the aerial hasnt worked.

Saw a cheap one on ebay, few questions.

There is no continuity between the metal circular plug and the the screw thread at the top of the aerial?

Is that white plug a power plug or an earth?

[h8v]

As I recall, the extra wire from the areial mount is for a 12v supply which can be either from the electric aerial output from the radio, or from the amplifier "switch on" lead, or probably more easily from an "ignition on" source.

The coax cable goes to the radio aerial input of course, and I think the earth for the amp in the aerial is either through the aerial cable screen, or through the roof mounting.

Hope it all works well.

[maxp]

So could the reason my existing aerial does not work be because it is not getting a 12v signal?

Also does where is the other end of the 12v, somewhere in the dash where the stereo is supposed to sit?

[h8v]

Having no supply 12v to the aerial amp could indeed be your problem.  There should be an original 12v wire somewhere above the headlining.  Failing that try a temporary wire straight from the extra wire on the aerial, direct to the battery +ve terminal to see if it makes a difference.  If it does, then you can set about about wiring it up properly.

I bought a replacement aerial from GSF a feww years ago, and it didn't have the amplifier in, so I went back and exchanged it for the amped version.

It's possible that VW changed the type at some time in the past??