No AM stations...but it's NOT the radio!

MalibuBob · #1 01-10-2007, 09:22 PM

This is weird...
A week or so ago I noticed that the aftermarket radio in my '05 Malibu (sedan with rear window glass antenna) wasn't getting any AM radio stations...nothing at all, even in my city which has LOTS of AM stations.
It did recieve AM stations at one time with the aftermarket radio, so I figured the radio went partailly bad. Last night I replaced the radio with a brand new one, and STILL no AM. FM works fine.
I don't think its the antenna, since I'm able to pick up all the local FM stations, and even some that are quite a ways off (40+ miles). Or maybe it is.
I'm at a complete loss as to what is wrong. I'd appreciate any help!
Thanks...

BeatnikTermite · #2 01-11-2007, 08:33 AM

Try this:

http://www.automotiveforums.com/vbul...d.php?t=324064

MalibuBob · #3 01-11-2007, 10:56 AM

Thanks for the link. I did check that, but it doesn't look as though the antenna calbe runs in through the same place on the 2005 models.
On the way to work this morning I let the radio "seek" FM stations and it found over a dozen. I was on an interstate and about 20 miles from the nearest towns that have stations. It looks as though FM reception is fine but AM is dead.
I've been told that there is an amplifier somewhere in the antenna system for the Malibus with the rear "in the glass" antenna. Anyione know if the amp is for FM or AM and where it is? I'm wondering if it's dead.
Thanks!

HyperFox · #4 01-12-2007, 04:56 AM

You lost AM? Wierd.. Normally for Z-body's is you loose your FM stations when the defrosters on.

So far as I can tell there is no booster so to speak of. Just the cable that runs to the back. Id get outside and look at the antenna lines with a magnifying glass to see if there are any hairline breaks..

Otherwise there is gonna be a lot of

MalibuBob · #5 01-12-2007, 07:42 AM

Quote:

Originally Posted by HyperFox

You lost AM? Wierd.. Normally for Z-body's is you loose your FM stations when the defrosters on.

So far as I can tell there is no booster so to speak of. Just the cable that runs to the back. Id get outside and look at the antenna lines with a magnifying glass to see if there are any hairline breaks..

Otherwise there is gonna be a lot of

Man, I was afraid of that. I did read about the problems with the defroster, but this is happening regardless of the defroster setting.
I think there is something in the car (other than the defroster) that is generating a signal that is killing the AM signal, but I'm not sure what it is.
Just for the heck of it, though, I may unplug the factory antenna and plug in another one and see what happens.

ShadeTreeBill · #6 01-13-2007, 08:37 PM

It is a classic symptom of a bad antenna system for the AM to not work, but still pick up FM. It's probably not picking up FM as well as it should though.

I am not very familiar with this antenna system, as I haven't had this problem (yet) on my BU.

If there is another connector at the radio I would check that...

MalibuBob · #7 01-13-2007, 11:22 PM

Quote:

Originally Posted by ShadeTreeBill

It is a classic symptom of a bad antenna system for the AM to not work, but still pick up FM. It's probably not picking up FM as well as it should though.

I am not very familiar with this antenna system, as I haven't had this problem (yet) on my BU.

If there is another connector at the radio I would check that...

I was finally able to locate some service information on this system, and there IS an amplifier for the in-glass antenna. According to the diagram I have, its in the headliner right at the rear window. As soon as I get a chance I'm going to see if its getting any voltage, and then see what transpires from there.

MalibuBob · #8 01-20-2007, 02:08 AM

Well, after taking the dash board apart again, I finally solved the problem...
There is an amplifier for the antenna for the X-body sedans. The sedans have the antenna imbedded in the rear glass, while the Maxx models have a regular "stick" antenna.
When I installed the aftermarket deck I also used a wiring harness I bought to integrate the deck and the cars wiring. One of the wires on the harness was marked "Amp" which I of course assumed met an audio amp. In reality, it's the antenna amp... Once I hooked that wire to the 12V switched wire, the AM perked right up.
It's nice to have the AM back.

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