Checking the lamps (Mercedes-Benz Sprinter 903)

This task is performed by an electronic device located in the relay block. The wires of the controlled lamps pass through the device. If there is no current flowing to the lamp, although its switch is on, the lamp failure indicator light comes on in the instrument cluster. You need to determine which lamp has burned out yourself. These may be low and high beam headlights on the left and right, front and rear side lights, front and rear fog lights, reversing lights, brake lights and license plate lights. The following should also be taken into account:

• when the ignition is turned on, the self-diagnosis lamp lights up. When the engine is running, it goes out if all the lamps are working properly;
• if the control lamp lights up when the engine is running, one of the lamps has burned out;
• the control lamp lights only when the device is turned on with a faulty lamp;
• if the brake light bulb burns out, the indicator light will come on when braking and go out when the ignition is turned off;
• the trailer socket must be connected according to the diagram.