Is this normal? My 2002 civic had this problem too.

 

Never heard of that before. My brake pedal feels slightly different when the AC compressor kicks on, but never when it's wiping. I hear the click of the relay when it makes a pass, which I assume is normal for this car, but nothing more.

 

If the wiper transmission is loose it could be clunking aginst the firewall and you could be feeling the clunk due to the brake m/c being bolted to the firewall. Shut the key off with the blades halfway up and see if there is any slop back and forth. There should be minmal slop, and no clunking.

 

I checked this out at work today and noticed it on numerous Fits. Having said that, it was VERY subtle and had you not said anything, I would never have noticed it. At the worst it was just a minor pulse and not an earth-shattering thud and on most it was practically non-existent.

 

Same here.