One of my jobs at the shop was (unfortunately) noise. Sound can transmit and make you think its somewhere else. Believe it or not, I had to go to classes on noise diagnostics.
Finding noises can be difficult and very time consuming. Once you find them, its not too hard to cure.
Its pretty much impossible to do any diagnostic over a forum. You need to carefully inspect everything. For me, I can only give ideas. Most may not apply to your vehicle but, I don't know what will, without having it in front of me.
The airflow across the roof can cause a variety of issues. This is why roof racks should have wind deflectors. This is for air noise but depending on panel placement, the panel can still be subjected to the force.
Another item mounted Infront of your panels/wiring will cause the airflow to change, this may also effect things.
The best way to do this is eliminate things that are "not" the problem. NEVER say cant happen. Prove its not the problem. If your inspection comes up with nothing, remove items one at a time and see if the problem goes away.
This means you need to be able to duplicate it many times.
Try not to shake, move or shift. more than one thing at a time. If you strip your roof and the noise is gone, which part was the issue? When you put it back, if the noise returns you did all the work for nothing. Now you start over.
Don't be impatient, take your time.
Some questions. Again, Its possible some or most may not apply
1. How long have they been there. If a while, have they always rattled or did this just start.
2. Have you done any work on the vehicle at all before the noise started. This includes removing a skid plate to change oil.
3. How do you know "exactly" its the panels and not one of the crossbars.
4. Assuming their rigid panels, how close are they to the front edge of the vehicle.
5. Does this happen at low speed only.
6. How are the connectors and wiring secured.
Here's a few symptoms and things to check.
Dirt road/low speed issues
Low speed issues can be caused by wiring and connectors loosely secured and "tapping" from road vibration.
This tapping will apply to everything on the roof as well as something inside the vehicle.
Even though hardware is tight, it doesn't mean what its holding cant move around.
Highway only noise.
Wind buffeting on the roof can cause a pulsating noise. Its normally a bit deeper then a rattle.
Chattering (pulsing squeak) will be caused by something not loose but not tight enough. Its moving just enough to be noisy. It will normally be a high pitched noise. This will be caused by buffeting.
Wiring and (or) connectors slapping the roof due to wind buffeting is common.
I recently helped a friend with a bad rattle. He swore it was from his rear suspension. The noise was his jack under the seat. The sound transmitted and he swore it was louder with the window down and it was way behind him. To me the noise didn't match loose suspension.
If you cant regularly duplicate the noise, your job gets harder.
