I picked up my RTL-Navi last week. I was very concerned that I would have problems with AM reception after reading many posts about poor performance on AM. I like to listen to local sports and talk radio in the morning on AM. I have been very pleasantly surprised to find that the AM performance is exceptionally GOOD. I live in the mountains in Central PA and the local AM stations are usually only good for about 40 miles. The Ridgeline has outperformed all other vehicles that I have ever owned. My wifes Acord is close. There is no static from bumps. Overall, I am very pleased. The FM volume is very low compared to all other modes.
Here's a long shot for you. I probably am telling you something that you already know but just in case, here is an idea or two. You may be experiencing electrical noise from a poor connection elsewhere in the truck that does not have any connection (no pun intended) to the radio. A switch that is out of adjustment and is just on the verge of turning on or off may arc and cause the type of noise that you are looking for. Try tuning a very distant weak AM station and turn up the volume. That should make electrical noise really loud. Have someone push and pull on the tailgate and the trunk to simulate if maybe the light switch is just on the edge of turning on when you hit a bump. You can push, pull, and wiggle any wiring that you can get to. You might get lucky and find a bad connection or a bad ground just about anywhere. Dont forget to check the brake lights too. Check both ends of both of the battery cables. The other thing that you can do is to turn your truck radio on but all the way down. Take a cheap transistor radio and tune a weak AM station. Repeat the same steps as above. If you hear the same noise on the transistor radio, something in your vehicle is radiating the noise. That usually points to something not directly associated with your truck radio or antenna. You might be able to narrow down the search by using the transistor radio to sniff for the source. If you hear the noise when the lights are on but no noise when they are off, it could be something as simple as a defective or loose light bulb or a bad socket. Tail light and side marker light bulbs that have a brass base usually have their negative wire soldered or tack welded to the brass base where the brass meets the glass bulb. If that connection is bad, those bulbs draw between 1 and 3 amps which is more than enough to cause a small spark and the noise that you are experiencing (when they are supposed to be on). These type of intermittent electrical problems are a real SOB to find. Good luck.
