The main beams are controlled by electronic Check device M45 , that receives control signals from the switches and controls the bulbs while also checking the various lines.

Check device M45 is supplied directly from the battery. (maxifuse CENTR of B5 ) to pins 1 and 6 of connector C, via fuse F11 of junction unit B1 .

An ignition-operated power supply (INT/A) reaches pin 9 of connector C through fuse F1 of junction unit B1 : pin 7 of connector C is earthed.

The device M45 receives as an input the signal for rear fog lamps switched on by the button located in unit H35 - pin 10 of connector A; this signal only arrives if the side lights are on. If, in addition to this signal, there is also the dipped beam headlamps on signal - pin 6 of connector B - or front fog lamps on signal - pin 2 of connector A, the device M45 then sends the supply to the rear fog lamps in the central rear lights clusters F35 (left) and F36 (right), from pin 10 and pin 4 respectively of connector E of M45 .

At the same time, a signal is sent from pin 3 of connector B to the unit H35 to light up the LED near the button indicating the 'rear fog lamps on' function.

The supply for this LED for H35 is controlled by the ignition (INT/A) via fuse F5 of junction unit B1 ; this line allows the control panel H35 to be lit up when controlled by the ignition (INT/A).

The device M45 checks the efficiency of the bulbs and their connections: if faults are detected in the circuit, the 'lights fault' warning light on the instrument panel E50, pin 7 of connector C, is lit from pin 6 of connector A, while pin 15 of connector A supplies an ignition-operated power supply to the panel through fuse F1 of the junction unit B1 .