does it only occur when van moving? if so it might be speedo cable as
you guessed. if so, try lubing... disconnect cable from speedo head
(either a pinch clip affair or screw on, depending on van year, should
be obvious), some light oil in the cable.

alistair

On 20-Feb-11, at 12:52 AM, Robert Stewart wrote:

> Rob,
>
> Thanks the reply. This most definitely comes and goes. It sounds
> like it's a weak electrical short but with a strange frequency I
> have never heard before. Definitely not the any pressure/coolant
> etc. alarm sound.
>
> Which relay is the Turn signal unit? How might I test to see if a
> relay has gone bad?
>
> The weird sound seems to be coming out of the speedometer to me or
> the lights above the speedometer/odometer. Could they be burning out?
>
> Could it be the speedometer cable whining at high speed and just
> making a noise? Could I somehow spray lubricant where it connects to
> the module in the dash to solve it?
>
> Thanks,
> Rob