[mdrush]

I've had the same problem on my 98 LT for years now...tried a new flasher relay, tested the brake switch all to no avail. Over time I've noticed it happen more consistently when the air humidity increases.

I rember reading on this forum that this is a know issue with the multi-function signal switch...apparently grease eventually drips down into the column and causes a low voltage short that triggers the relay but not the lamps. Solution was if i recall to replace or clean the multi-function switch at the base...requires removing it from the steering column..doesn't bother me enough to go to all that work.