loud humming noise
 

Hello,

I've recently acquired a 2004 S80 T6, and have noticed that with the key in the I or II positions (i.e. without actually turning the engine on) there is a very loud and steady humming noise coming from the left front corner under the hood (i.e. behind the driver's side headlamp). The under-the-hood diagram in the owner's manual seems to indicate the air cleaning system is near there -- could it be that, maybe fan noise?

I can't really tell if the sound continues when the engine is turned on (if it does, the engine noise drowns it out).

Ultimately I'll have my mechanic check it out, of course, but thoughts on what it might be would be appreciated... thanks!

Is it a round chrome looking thing?

It's hard to say exactly where the noise is coming from. The closest thing seems to be the large black box that corresponds to the air cleaner in the diagram in the manual, although it could be coming from lower down by the headlight assembly.

Sorry for the vagueness. Anyway my mechanic's going to have a look tomorrow (Thursday).

Diagnosis: there was a short in the headlamp wiper motor.

That was going to be my next guess.