Detection of a faulty consumer (Mercedes-Benz Sprinter 903)

If a battery that was working properly the day before suddenly stops producing current, it is possible that a faulty consumer in the circuit has discharged it overnight. This should be checked by first measuring the current in the circuit. If necessary, identify the faulty consumer. This must be done as follows:

• remove the negative terminal from the battery, connect the wire of the universal tester between the negative terminal of the battery and the "ground". If the tester shows the presence of current, there is a faulty consumer in the circuit;
• reconnect the negative terminal, open the fuse box and remove one fuse. Connect the tester wires to the fuse contacts. If the device does not show current, the circuit of this consumer is OK. A small amount of current is acceptable. Devices such as watches, radios or alarms constantly consume electricity from the battery. However, the current in their circuit is much lower than that of the faulty device;
• continue measuring on the fuse box until you identify the device in whose circuit the high current is flowing. The fuse chart in the owner's manual will help you determine which device is connected through a given fuse;
• disconnect the suspected consumer and measure the current. If the tester no longer shows current, the faulty device has been detected.

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