No check engine light, Service is done at dealer hope its just spark plugs lol, i replaced a pack 2 monts ago, i think the codes are the best rout, i was hopping it was something one of you had this problem too... and we can work this out.Do you just have the TRAC OFF light on, or also the check engine light? If you also have the check engine light on then it might be a bad coil pack, or the spark plugs might be bad causing a misfire, which both cause violent shaking. You might want to get the code scanned at an auto parts store and work from there. Replacing spark plugs or coil packs are an easy fix and the car does not need to be taken to the dealer for this.