1. Provide conditions under which voltage is present at the control points.
Example:
- (A) - the ignition switch is on.
- (IN) - the ignition lock and switch SW1 are on.
- (WITH) - ignition lock, switch SW1 and relay are on (switch SW2 off).
2. Using a voltmeter, connect the negative wire to the point «masses» or negative battery terminal, and the positive wire to a connector or component lead.
Note. Instead of a voltmeter, you can use a test lamp.