Speaker hum after hitting a bump

[Shdwdrgn]

2004 TB with the Bose 6-disc player. This is *very* intermittent, occurring maybe once every month or two. Basically if I hit a bump, or go over some rough tracks, I will start to get a loud hum out of the speakers (seems to be louder on the right side). There's a general buzz that never changes, but underneath that you can also hear a whine from the engine speed, and even clicking from the blinkers. Shutting off the stereo makes the sound go away, but comes back when you turn the radio back on. However shutting the ignition completely off then restarting the truck makes the noise go away.

My guess is that this is coming from either the amplifier or (if there is one) a noise filter in the audio system. Since it only happens when I hit a bump, I thought it could simply be a loose or dirty ground...

So where to start? Any suggestions here would be helpful. And where exactly IS the amplifier located? It certainly wouldn't hurt to check any plugs going between the amp and radio.

 

[Blckshdw]

Check the splice pack at the bottom of the radio stack, on the passenger side, behind that flap of carpet. Make sure that bolt is tight.

 

[Reprise]

I've had this exact same problem (even down to the same speaker). Started this fall; stopped when the weather got really cold.

I also get distortion out of that speaker after the amp has been running a while - and I generally don't listen at loud levels. After the vehicle is shut down for a bit, noise is gone at startup - for about 30min or so.

So...I'm pretty much of the opinion that my factory amp is the cause. I've got a replacement ready to put in once it gets warmer. Although I will check out that bolt that @Blckshdw mentions - if it is the cause, at least I won't have the noise any longer until I get around to replacing the amp.

(on edit - unlike the OP, I don't believe I've ever heard the noise he describes through the blinkers. So he may have more of a chance finding the bolt loose than me)

 

[Mooseman]

I would also imagine that the amp has a built-in noise suppressor that could fail.

 

[Shdwdrgn]

Sorry for the delayed reply! For some reason I never got my usual email notifications that there were replies to my thread and I just decided to check up on it today. Anyway...

Thanks BlckShdw, I'll check on that bolt tonight. As I mentioned it is a pretty infrequent issue and hasn't happened again since I posted, but it's only a matter of time.

As Mooseman mentioned, I would also agree it sounds like a noise suppressor issue. Back in the day when I got a new stereo for my old Pontiac, I had pretty much exactly the same kind of noises coming from the amplifier, and had to get a noise suppressor from RadioShack to fix it. I had the same kind of issues, including hearing the clicking of the blinkers through the amp.

I'm about the chuck the factory stereo anyway. Reception is so horrible that the original owner installed a signal booster -- even with that on I still had sporadic (easily blocked by hills and building) reception of the most powerful stations while driving around Denver. I even picked up another of the same model and used it in test mode for a few days, and had exactly the same problem. I've had better reception on garage-sale radios without an antenna. BUT the Bose amp has been working great except for this hum, and there's plenty of harnesses available to retain that equipment.

 

[Mooseman]

there's plenty of harnesses available to retain that equipment.

Yes, choices available from PAC (my current setup) and Metra (I have had a couple of these fail on me). I also had to add a suppressor between the HU RCA out and the RCA in of the adapter as I was getting alternator noise.