Starting System Description

The Ignition Switch is a multi-contact rotary switch containing five layers or sets of contacts. As the ignition key is rotated, various contacts in the five layers operate to open or to close. The contact development for each switch layer depends upon the position of the rotary switch. The switch has four maintained contact positions and one momentary contact position. These five positions are the Accessory (ACC) position, the Lock position, the Off position, the Run position, and the Start position. The Start position is the momentary contract position. The Start position is only operated by holding the ignition key in place. These five switch positions control the operation of the ignition circuits.

The ACC position is used to operate either the radio, the wipers, or the overhead map lamps while all other ignition circuits remain de-energized. These components are also available with the Ignition Switch in the Run position.

The Lock position is the position in which the Ignition Key may be removed from the Ignition Switch. Otherwise, it is identical to the Off position.

The Off position is the position in which all ignition circuits are de-energized. However, the Ignition Key cannot be removed from the Ignition Switch while in this position.

The Run position energizes all ignition circuits with the single exception of the Start or Crank circuit. The Run position is the switch position used while the vehicle is operating.

The Start position is sometimes addressed as the Crank position. In this position, the Starter is energized in order to start the engine. Depending upon the vehicle's options, this position also sends signals to various control modules. These signals inform the control modules that the engine is being started. The function of these signals is described in the appropriate system description.

Some electrical loads are operated with the Ignition Switch in either the Run or the Crank position. The switch contacts for these loads do not open as the Ignition Switch is moved between the Run and the Start contacts. Voltage continuity is maintained.

There is no Bulb Test position. However, not all of contact layers may operate at the same time. Four of the sets of contacts are closed in the Run position. By moving the key slowly from the Off position, it is possible that some of the Ignition circuits will be energized before the others. However, it is not necessary to do this as the bulb check function is fully demonstrated by the electrical systems while the Ignition Switch is in the Run position. The bulb check functions are described in the appropriate system descriptions.