I’ve had an aftermarket head unit in my 99 Ram for years with no issues. Went Tuesday to have a local shop install 6x9’s, tweeters, 6.5’s and an amp. For the most part everything is OK but I am having a big issue with the AM radio. It has some kind of “feedback” or noise In the line and the local shop is stumped. They tried to redo the ground wire on the headunit as well as try some adapters (noise filters maybe?) in line with the antenna. Nothing works. It is so bad you can’t even listen to AM radio. One strange thing is that the noise gets quieter when the blower (from the vent) is on a higher setting.

The installer is stumped.

Does anyone have any ideas what it could be?

 

My question...why listen to AM?!?! I am stumped also because I would assume the ground first but that would effect all quality. Hmm...

 

Just some local talk show that I listen to on occassion.

 

My only last thought is some after market stereos AM antenna is a different wire that runs out...but you seemed to checked that.

 

The manual only shows one antenna.

 

Maybe try a ground loop isolator? Does the sound whirrrr up and down with the RPM's of the engine?

 

AM stations are on a lower band width there for making it easier to pick up other electric noises. I would try taking the amp out of the loop and see if that solves the problem. If it does see if you can get your installer to put a filter on the power wire to your head unit.

 

No, it's not typical engine noise coming through thespeakers.

He said he's gonna look into it and get back with me. I can ask him to take the amp out of the equation but he would have to re-run speaker wires to the back of the head unit, right?
And if it doesn't do it then would it mean there is something wrong with the amp????
Not sure what I would do at that point.


He tried one adapter (I believe he said it was a filter) but it didn't help a bit.

 

I'd strongly suspect it's the amp causing it. Maybe try grounding it different places. The sub amp in the 96 Accord does this too. I put the amp on a switch so I can turn it off when I listen to AM stuff and just have the sub off. This obviously wouldn't work if you have the amp powering your speakers. It was the easiest method for me but usually it's where it's grounded.

I'd almost bet it's the amp causing your problems. Try grounding it elsewhere first.

 

Thanks. I'll try and get a chance this weekend to see how they grounded it. But I know at first I was getting major engine noice while revving the engine so I took it back and they "fixed" that problem. Then, after I left that day I noticed the AM thing.

If anyone can think of anything else in the mean time please let know.