Weird radio problem....

[gavs]

Hi all,

Just after some advice regarding a problem with my stereo. I have a pioneer head unit, standard door speakers and a pioneer 12" sub.

Initially thought this was an issue due to my car not having an antenna when I bought it, but putting an antenna on hasn't fixed the problem.

When i'm listening to a CD or aux input, the sound is fine, crystal clear. The reception of FM band is clear also, I cannot fault it at all. Recently i have started to listen to the AM band more frequently, but when I'm driving it's near impossible to get a clear signal.
The symptoms of the problem are as follows:

*Reception fine when ignition is at the ACC position.
*Ignition turned to on, will get rythmic pops but the reception is still fine.
*Started engine, reception is over-run with static and the radio now transmits the sound of the engine.
*It's through all speakers, the only speaker hooked up to the amp is the sub.

This is really bloody annoying, especially during the recent bushfire season when I couldn't get any info from ABC local radio.

Things I have tryed to fix it:
*New antenna.
*Disconnected amp and sub.
*Cleaned amp earth point.
*Connected a little black box that was on the head unit i took out which i think MIGHT be a noise filter..

Thanks for any and all help.
Gav

[glidn]

i would be inclined to check your earth on the radio itself.

I had a simlar issue when i had my mk4.

that is what it turned out to be.
Run a positive and negative from the battery to the radio around 10awg.
then just use the remote from the wiring loom and of course the speakers inputs too.

this should rectify your issues.

[gavs]

Thanks glidn, will give this a shot.

I pulled down the rear of the headliner to get to the antenna cable, see if it was ok, and after fiddling around with it, it helped clear it up so i think you're right, i think it might be using the antenna wire as a ground....

[gavs]

Well, I now have a definative earth for the radio.

It didn't help.

I plugged the head unit in, after pulling apart the entire centre console, turned it on and it worked. Thing is, I hadn't even connected the earth yet!! So somehow it was creating a circuit without using the earth wire of the radio loom!!!!

This has now lead me to believe that (aside from the Mk4 wiring issues) the head unit is using the antenna as a grounding instrument. I once again pulled down the back of the headliner to have a fiddle with the antenna cables and it cleared up the signal. I am thinking that the cause of the situation is the dreaded missing/cracked seal at the base of the antenna, where it meets the roof. This was cracked when I purchased the car and has since disappeared altogether. My hypothesis at this point in time is that moisture has probably gotten in there somewhere and has started to corrode something, resulting in part of the connection forming an earth-point with the car body.

When I get off my ar*e to try and fix it, I will let all know of the results, this could be a hidden issue with the failure/disintergration of these little seals.....

Hopefully it's not a new antenna job, don't feel like spending $350 on one!