Work must be started only after 90 seconds from the time the ignition switch is turned to the LOCK position and the negative battery cable has been disconnected. The SRS is equipped with a back-up power source so that if work is started within 90 seconds of disconnecting the negative battery cable, the SRS may deploy. When the negative terminal cable is disconnected from the battery, memory of the clock and radio will be canceled. Before you start working, make a note of the contents memorized by the audio memory system. When you have finished work, reset the audio systems as before and adjust the clock. To avoid erasing the memory of each system, never use a back-up power supply from outside the vehicle.