Immediately after starting my ML-320 when it's cold I hear a fairly
loud, high pitched and steady tone which appears to come from either
under the dash or the engine compartment. When the engine warms up this
"tone" stops abruptly as if it was switched off. The noise may not
re-appear until the next morning. Of course I can't make it occur when
I have driven to the dealer.
I don't think it's a fan that is making the noise.
Any thoughts would be appreciated.