Final Rattle Update
First, note that the sections on this page are in reverse chronological order. The "What Is The Rattle" section was written before the cause was known. The "Original TSB Info" section was written when Toyota first released the TSB for the rattle (before I did it on my own RAV). This section is hopefully the final chapter now that I've done the TSB and the problem is fixed. The fix on my RAV involves both a modified version of the Toyota TSB and a fix to the battery cowl cover that while isn't really a contributor to the primary rattle is probably a good prevention measure for future problems. Look at both fixes and decide for yourself what you want to do. Note that if you take your RAV to the dealer for the TSB you're not going to get the fix illustrated here. I don't believe the factory specified TSB is going to work as well. Since the method that I describe here for the modified TSB takes less than an hour and costs only about $2.00 I think it's worth doing it yourself. If you want to do the battery cover cowl fix while you're in there it will probably take 1-1/2 to 2 hours total and cost about $10.00. In either case, it's less time than the trip to the dealer and the wait for the car. Here's the detail on the two procedures. Read the rest of the info on this page as well if you care about more background.
Original TSB Info
As of Feb 23, 2001 Toyota has issues an official TSB (Technical Service Bulletin) for the Windshield Cowl/Dash Rattle Fix. The complete TSB can be found on RAV4WORLD.COM HERE. Other related rattle TSBs and general TSBs are on RAV4WORLD.COM HERE. Note that the Dash Rattle TSB focuses completely on the large cowl section and does not even mention the fixes the I detail below. It's going to be up to each individual to determine whether the official fix addresses everything or whether they want to do more. My opinion is that my fix is still worthwhile in that it eliminates the flimsy mounting for the cowl that will probably result in new rattles in time. There are many posts on the RAV4WORLD.COM RAV4.2 forum about the rattle, the results with dealers and individuals applying the TSB, etc. It's worth reading these to get the benefits of other owners experience. One particular note is that numerous owners have had problems getting their dealers to perform the TSB fix or were unhappy with the results. The TSB should be easy enough for the owners to do themselves. All that is required is some felt that can be found in a home center, hardware store or fabric store. Again, it's all up to you...
Note that there is a second TSB that provides rattle fixes for several other types of rattles other than the dash/windshield rattle. Not as many owners seem to have reported these, but if they show up Toyota has a prescribed fix.
A final note on the dash/windshield rattle and the fix information below is that I no longer believe that the rubber strip on the edge of the cowl contributes to the rattle. Although several users report having the rattle go away after removing the strips, I believe that this is coincidence. I think that the removal of the strips shifted the cowl in a way that stopped the rattle for a while. I had placed both felt and foam strips between the rubber strips and the windshield. Even with these in place the rattle came back. One of the last steps I took was removing the felt and foam (and leaving the rubber strips in place) and the rattle disappeared again. In the course of performing and documenting my fixes I've had the cowl on and off many times that the reappearance of the rattle has been seemingly random with the various removal and reinstallation attempts.
Now - on to the history.....
What Is The Rattle
It appears that nearly 100% of the 2001 RAV4s manufactured to date have what has become known as the "Dash Rattle" or "Cowl Rattle" or "Windshield Rattle" or most simply, just "THE RATTLE". It is a "tic-tic-tic" sound that generally comes from the right side (passenger side U.S.) of the dash. It sounds like a piece of metal or hard plastic being tapped against the windshield. Toyotas TSB indicates that the rattle is coming from the retainer clips that connect the large cowl panel to the windshield. The TSB fix involves applying felt pads to these clips. Previous to the TSB the most common theory was that the rattle was coming from the cowl panel that covers the battery compartment. The cowl is the black plastic section that can be seen between the windshield and hood when the hood is closed. The first photo below shows the battery compartment with the battery cover section of the cowl removed. The cowl over the battery cover is held in place with plastic screw/clips that are designed to be removed without tools (using a coin to turn the screw) so that the owner can access the battery. The problem with these is that they don't hold tightly in the first place and get worse each time they are removed and reinserted. The overall affect of this is that the cowl cover (which isn't padded in any way) has a tendency to rattle against the support members and the screw/clips themselves tend to rattle in retaining holes. The second problem appears to be that the rubber strip on the edge of the cowl cover that touches the windshield tends to tap on the windshield. This seems to be worst when the weather is cold and the rubber is stiffer. Another suspect is the red plastic cap that covers the positive terminal of the battery. It isn't fastened down in any way and tends to bounce up and down and click against the battery case. The final suspected culprits are the larger cowl section (which is attached with plastic body fastener "rivets" similar to the screw clips) and some of the ducts, wires, hoses, etc. that go through the firewall. The large cowl panel has the same rubber edge against the windshield, so this is a potential issue. The body panels and support members under the large cowl are foam padded by the factory, so this shouldn't be an issue. The plastic rivets seem to hold much tighter than the screw/clips so this doesn't appear to matter either. I also haven't personally seen any evidence of the ducts, wires, etc. that go through the firewall contributing to the rattle. The location of the rattle and the noise itself don't point to this as an issue.
So now what? Over the past month I've experimented with numerous solutions and as detailed below I have the rattle about 90% eliminated on my RAV. The remaining 10% is definitely NOT due to the cowl in any way since the rattle is still present if I drive it with the cowl completely removed. The remaining 10% is now my quest and I won't rest till I've fixed it!
As you've read above the "final 10%" is due to the problem addressed in the TSB. Performing the modified TSB has cured the rattle 100%.