OK, i have a 2001 oldsmobile alero and when it rains heavy my traction off light comes on on the dash and it stays on, and when I shift into drive or reverse it makes a very loud booming soud and the engine slams back and forth really hard. When driving down the road when it shifts gears it shifts really hard but the transmissiondoesnt slip or anything. When the roads dry up and it stops raining the light goes off and everything goes back to normal, if you drove it you would never know anything is wrong with it until it rains !!! HA HA weird i know, any advice ???? Had it hooked up to a computer and it reads no codes.