After I installed a MTX 4 channel amp under the driver seat and replace the rear 6x9" speakers, I heard the strange high pitch 'weeee' sound inside the cabin. It gradually increase when the revs starts going up and disappears when the car stops.

The sound is still there even I turned off the stereo so it is not from the speakers. Is that some sort of circuitry or electrical problem?

Also after they took the interior apart (including the airbag plugs) for the installation, the air bag light on the dash comes on when I start my car, did they screw up the connections or is merely a precautious measure everytime someone tampered with the airbag connection, which need to take back to the servicing for resetting?

Would any electrical enthusiasts out there give me some answer just to ease my mind before I take back to the servicing?:confused:

They've cocked it up. The high pitched whine is coming from a bad earth and the airbag light shouldn't be coming on... take it to your dealer to check that one but ensure the place that fitted the amp will pay for it...

Dom

Ignition must not be turned on while seat connectors is disconnected.
The car's computer will detect a fault in the airbag system and the indicator must be reset by a Mini Service shop.

A high pitched whine is normally caused by ground loops (current flows in ground leads. The whine is made in the generator.
To correct this, check all connections for signal and other ground connections.
Use good leads directly to battery for power supply, and beware of signal lead shield connections.
Regards, Tore

check out this link for help

http://www.mini2.com/forum/showthread.php?s=&threadid=21643

if you're getting the whine with the radio off, i assume the amp is still powered on? that tells me there is a ground problem with the amp. that might not be the only problem, read the above thread for ideas.

The whining sound disappears this morning I run my car. What actually happened? Do I still need to fix it or I just need to take it back to check the grounding anyway.:confused:

Thank you for all you guys help!

i would still double check the grounds, if it just "went away" it could be a loose connection--which would also be very bad. i assume they wired the amp through a fused power connection? if somethings loose you still want to car to be protected. rarely do things just "go away" permanently.