There are at least 16 such modules that control virtually everything. Your inside rear view mirror is the upper module. 2 modules required to blow the horn. 3 required to open the pass front window from the drivers door. The list goes on. 1 module in each front door, 1 in the trunk, climate control, speedo cluster, radio, engine, trans, power seat, etc. The most common ones that go to "sleep" are the upper module, and the steering wheel module. If that one goes to sleep, steering wheel controls for radio, cruise, turn signals, and wipers stop working. To wake it up, remove the steering wheel module fuse for a couple of minutes with the key off. This usually wakes it up and functions return, however, If this occurs, a trip to the dealer is in order for fault tracing. Fortunately, this problem is not widespread, but does occur. F.Y.I.