Whenever the current flow through a coil of wire (such as used in a solenoid or relay) stops, a voltage surge or spike is produced. This surge results from the collapsing of the magnetic field around the coil. The movement of the field across the winding induces a very high voltage spike that can damage electronic components. In the past, a capacitor was used as a “shock absorber” to prevent component damage from this surge. On today’s vehicles, a clamping diode is commonly used to prevent this voltage spike. By installing a clamping diode in parallel to the coil, a bypass is provided for the electrons during the time the circuit is opened (Figure 15-7).