Weird A.M. Radio Static in a 2006 Malibu Maxx

radio

#1

I have a 2006 Malibu Maxx (3.5 V-6) that has A.M. radio reception problems. You can hear all stations clearly and then suddenly overwhelming static mysteriously appears, typically when I hit a bump. The dealer has replaced the radio with two additional radios and they have checked every ground and the antenna. After they tried their last fix, if I step hard on the brakes, the A.M. is clear. As soon as I let up on the brake pedal, the static returns. You can always hear the station in the background. The FM and CD work perfectly and the FM is static free.



I have had two new radios installed by dealer. That makes three different radios that all perform exactly the same. All grounds have been checked and tightened. The antenna has been checked.



The dealer can duplicate the problem. They have clearly heard the static and driven the car to duplicate the problem. They believe they get the problem fixed in the service department, and then as soon as they return the car to me, the problem reappears. If the car is moving and you hit the brakes, the static disappears. If you are sitting still and apply the brakes, the static remains. When you first start the car, the static is there immediately.



When I had the same problem with the first two radios, once in a while, if I hit the right side of the dash next to the radio, the static would disappear for a short time. It would usually return when I hit a bump in the road.



The dealer has contacted GM and checked for bulletins, but nothing has worked thus far.



I believe there is a bad ground loop somewhere and they just have not found it. I suggested running a ground directly from the radio to the battery. This is driving my wife and I crazy. Thanks for any help you can give!!!




#2

I think the antenna cable may be the problem. If they replaced the antenna and the radio, but not the antenna cable, that would be my next suspect. Oh, I see they “checked” the antenna. I assume it’s one of those in the glass antennas. I’d still be looking for a loose antenna cable connection and possibly a bad signal amplifier, if it has one.


#3

Thanks for the reply. The dealer tells me that they have checked the stick antenna and it’s fine and the tech states that the car has no amp. The weird thing is the effect of applying the brakes which causes the static to disappear, but only when the car is moving. Something must be shifting in the vehicle that completes the ground.


#4

I think there is a ground strap between the engine block and the body of the car. The strap may be loose. When you brake, the engine shifts on its mounts and makes the ground connection. I would certainly check this possiblility.


#5

It would be nice to know if the noise is getting into the radio through the antenna or the power lead. To see if the antenna is picking up the noise pull out the antenna lead to the radio while the noise is occurring. If the noise stops then you know the antenna is picking it up. If it is the antenna then I recommend the antenna ground be cleaned, reguardless if it “looks” ok. If the noise doesn’t go away when the antenna is removed then the noise is most likely getting into the system through the power lead. There should be some sort of noise suppressor circuit built into the cars system so that needs to be checked if it hasn’t been already. This is usually a capacitor tied between the power buss and ground.

I assume the noise doesn’t occur if the engine isn’t running but the ignition is ON. The ignition system is the most likely source of the noise. By running a heavy ground lead between the negative battery post and suspected bad ground points on the body you may be able to find the source of the noise.

Using a small portable AM radio as a detector may help you find the problem area also. Tune the radio in between stations and the closer you get to the noise source the louder the noise will be heard on the radio.


#6

If it has a stick antenna, then I’m back to the antenna cable. Loose, dirty, marginal connections in the antenna cable shield will affect AM first and may not affect FM at all.


#7

That’s a great place for the dealer to try again. Thanks! I discovered tonight that when the car is stationary. I can turn the steering wheel left or right and the static starts. Also, if I turn the ignition off and remove the key, the static remains for about 15 seconds, and then disappears! I have turned on all the accessories in different combinations and that has no effect on the noise, nor does the ignition as I accelerate.


#8

Thanks. I’ll share that idea with the dealer!


#9

Thanks. I’ll share your suggestion with the dealer. I discovered tonight that when the car is stationary. I can turn the steering wheel left or right and the static starts. Also, if I turn the ignition off and remove the key, the static remains for about 15 seconds, and then disappears! I have turned on all the accessories in different combinations and that has no effect on the noise, nor does the ignition as I accelerate.


#10

Since the noise still occurs with the engine off I would guess that the noise is coming from the ECU. Computers are a good source for noise. I can’t see why the steering makes the noise start unless it has to do with the some sliding contacts in the wheel.


#11

Cougar,

Thanks for the response. I am taking the vehicle back in to the dealer with the suggestions I have received> I’ll let you know what they found…if they ever find it!!


#12

I think the standard model uses electric power assisted steering. That would be a good place to start looking.


#13

It’s going to the dealer next week. The techs have never mentioned the electric power assist as a potential culprit . Thanks. I’ll have them check and let you know!