Nissan: Radio Noise

The vehicle is a 2000 Nissan Quest, about 45K miles.

I just had two warranty items taken car of. A new tranny was installed,
due to a whining while in 2nd gear, and during the same visit, the
radio/cd player was replaced because it no longer lit up.

When I got the van back, the tranny was fine, but the new radio now has
noise on the AM band. The radio is the same model as the one it
replaced. Here's the best I can describe it:

The noise doesn't sound like reception static; it sounds like it's
generated by the vehicle, and maybe getting into the radio via the
electrical system or antenna. It's sort of a crackling sound, like
cellophane, that DOESN'T increase in speed or pitch as vehicle speed
increases. Also, I can't find a correlation between gears and when the
crackling happens. Sometimes it's worst in 2nd, sometimes in normal
drive, and sometime while in neutral at a stop.

One thing that is consistent...the crackling is very bad when first
starting the van after a long time, like in the morning. It's only on
the AM band. Then, after about 10 to 15 minutes of driving, it's almost
all gone away.

It's like heck getting my dealer to diagnose anything the first time
around. Most problems with them are 'normal'. Before I go back to them
with this, I'd like to get some opinions as to what this may be. A bad
ground?

In article <net>, com says... 

I do. There's more out there than just music. For music I have my CD's.

Glenn