What's Pass Lock Code For 1999 Chevy Silverado Truck?

I have a1997 mercury sable with an aod trans, the car shifted quite ok
till I replaced the battery , now it shifts 123 with a harsh jolt  unless you use  a light accelerator pressure, when you use more than a light pressure
it really jolts you ,and seems like trans is confused as what gear to be in
jumps  back and forth