Before measuring the current strength, the measuring range is set on the device, corresponding to the expected value of the measured current. If the current strength is not known, then you need to set the highest limit and, if the device does not show any current, successively switch the device to the measurement ranges of currents of lower strength.
To measure the current strength, the electrical circuit must be broken, and the measuring device (ammeter) included in the chain break. To do this, for example, the plug is disconnected, and the red wire (+) ammeter is connected to the supply wire. black wire (-) ammeter is connected to the contact to which the disconnected wire was connected. Mass contact (-) between the plug and the current consumer must be closed with an auxiliary wire.
Attention! In no case do not measure the current on the wire to the starter with a conventional ammeter (about 150 A) or to diesel engine glow plugs (up to 60 A), because the ammeter may be damaged due to the large currents flowing. In workshops, current clamps are used for such measurements. The clamps are attached to an insulated wire and the current is measured using the phenomenon of induction.