High Pitched whistle through speakers, engine speed dependent???
 

I've searched and searched on this and come across nothing....

I have an '06 HHR 2.4 LT and I've had a chronic problem that I can think of nowhere else to ask but here.

I replaced the stock radio HU after it had prior problems where the HU would be on but no sound would come from any speakers. I was told by the dealership that it was faulty, and replaced it with an aftermarket HU (Sony Mex-BT2700, see link in my signature). The new HU has not caused this problem but now at seemingly random times, the front left and right rear tweeters will begin to make a very high pitched whistle/screech (think dog whistle, or that iPhone app that makes people clamp their hands over their ears).

Turning the volume of the radio up or down doesn't change the volume of the whistle noise- it stays loud, and the audio from the radio still comes through on each speaker, just overwhelmingly masked by the whistle.

The whistle sound stays at a constant pitch, but when I accelerate and my engine RPMs increase, the pitch goes higher!!?!? I can think of no reason why this could happen!

To stop the sound I generally have to turn the radio off, wait 5 seconds and turn it back on, though recently I have had to shut the engine off completely and start the car again! Both of these usually fix it for the remainder of my drive, but recently the whistle sound comes back after about 30 seconds which makes driving my beloved HHR a headache (or a completely silent experience with no radio).

I took it to the dealership three times now and they told me they couldn't fix it, or even replicate the issue (even once when it was happening, and the repair advisor witnessed it) but the technician couldn't find a problem or replicate the issue.

Any suggestions / assistance would be much appreciated- I love my HHR and don't want to start hating it every time I drive it because the radio gives me a headache!

It sounds like you have a ground loop. ( a poor ground in the stereo wiring) You might want to check the wiring done to replace the HU. Post pics if you could and I could try and help ya out....

It also sounds to me to be a ground loop problem. The tell tale sign is it changing pitch with engine revolution.

reviving old thread
 

I know this is a 4 year old thread, but, did anyone ever figure this out? I have the exact problem but I still have the original HU....I have an electrical diagram and I cleaned up all of the grounds. No luck. I'm thinking about pulling fuses one at a time to see if it will go away. Sound like a good plan?