I listen to AM in the morning going to work to check traffic. I get terrible static on AM and can change it by turning my dash light dimmer switch! I can totally defeat the static sometimes by turning the dimmer all the way down, and sometimes its the opposite, full on after the click. It also stops when I turn my parking lights (middle position). do I have a bad ground to the radio, amp or dimmer switch? I can run a dedicated ground from stereo to battery if need be, its driving me crazy. It also has a pulsing static when I go under an overpass, I think that may be related to the AIR BAG light? I removed the dash to repair some needle LED's and started the car without it connected so the air bag light went on, have not reset it yet. Could the needle lamp replacement (one didnt "take") cause this static? I dont remember it before this but I only got the car last year.

On another related topic, sometimes my FM sounds like crap too, like the amp is not working. I get very distorted FM on all channels, sounds like all the speakers are blown even at low volumes (like 1!) and doesnt get any better if you turn it up. Other times, it sounds fine. CD player works great, it never has an issue, even when FM is distorted, CD sounds amazing.

 

pishta,

I also use the AM setting quite often on my factory Pioneer stereo both in the city but especially while traveling long distances. I've never encountered the specific situation you have where the interior light dimming **** affects the reception but I feel everything else you've described is fairly consistent with the characteristics of AM reception. I get bad interference when traveling under overpasses, at some intersections and when passing certain buildings or power line structures. It has always been a messy, static and interference-prone low fidelity radio medium (honestly one of the most amusing and fun things about it to me!). It's only surpassed in janky "radio" characteristics by those of short-wave bands. FM clobbered it decades ago in terms of addressing all the interference issues you mention.

Now what you mention at the end of your post sounds separate. It could be that your factory Pioneer amplifier is beginning to fail. This can happen after some 24+ years. It is a particular design that almost no other aftermarket stereo uses or needs. If you have a factory Pioneer system you could seek out a new-old-stock OEM Pioneer amplifier on ebay (OEM P/N 86280-24151) or you could swap to a new stereo head unit and lose the factory amp system entirely... or you could rewire an aftermarket stereo to use the OEM Nakamichi SC300/400 amplifier if you can find one used since it is much more compatible with aftermarket stereos. I had my factory amp go out and I just scoured for an NOS OEM Pioneer amplifier to replace as little as possible in my SC300 and keep the stereo system 95% stock. I'm not a big aftermarket car stereo person so this worked out best for me.

However...

Even if you haven't performed the factory stereo aux-in jack DIY modification to test an open channel with you say your factory trunk CD changer/player still works well and has no issues as with the AM and FM settings. This makes me more closely suspect it could indeed be a grounding issue of some kind but more specifically somewhere from the antenna wire on the back of the OEM head unit back to the antenna assembly and motor itself in the trunk. I'm no expert regarding the OEM stereos but that would be my best initial guess. Take the above notes on the amplifier into consideration only if specific symptoms related an amp malfunction are noticed.

If it were specifically your amplifier having issues then I would think the CD and Tape functions would both have identical audio quality issues... excepting common AM and FM reception quirks.

 

Thanks. I replaced the OEM power antenna with a replacement stock type and made sure everything was plugged in and had a good scraped to paint ground on the mounting bolt back there. Sometimes its great but I never lose the terrible ground hum when I go under an overpass. Amp caps will be looked at...where is it, under the changer?

 

Yes, the OEM Pioneer amplifier should be located underneath the trunk mounted CD changer. I am not sure if a factory Nakamichi stereo has the amp in the same place though other threads here do cover both factory stereo systems and component locations in great detail.

Hope a simple ground repair resolves your issue!

 

^ They are in the same place, other than the Nak integrating the sub amp into the main amp, rather than it being separate up on the parcel shelf like the Pioneer system.

 

Thank you, t2d2! I couldn't recall if there were more differences (other than wiring) other than the subwoofers themselves and the parcel shelf sub-amp for the factory Pioneer system.

pishta, there you go!

 

My AM reception has been bad since I bought my car in 01. I replaced the Antenna. I think I need to run a new antenna cable to the radio. If I do that will the auto remote to unlock doors be terminated?
I read that the antenna cable and door locks use the same wire.

 

I wonder what the rear glass antenna does? AM or FM?

 

There is a TSB available concerning AM radio static.

it involves pulling the radio head an adding insulators.

I did this to my 1992 sc400 years ago, and it did help.

Even after these, reception is not great.

Also, the antenna can shift and cause the same thing.

Hope this helps,

Alan

 

It's really a losing battle, especially in older model cars. Although this might help?
http://www.popularmechanics.com/cars...o/a84/1272491/