Check of integrity of a chain is necessary to define whether is not present in a gap chain.

1. Disconnect tension from a chain and check a chain for integrity by means of a bulb with the connected power supply.

2. Connect bulb wires to the ends of a chain (or by the positive end and mass of the car); if the control bulb lights up, in a chain there are no gaps.

3. If the bulb does not light up, so somewhere in a chain there is a gap.

4. In the same way it is possible to check the switch, having connected a control bulb to switch plugs.

5. After turning on of the switch, the control bulb has to light up.