Audi A4

since 1994 release

Manual of the car

• At a control bulb in the combined device two plus connections: first, on the plug D + the generator (a blue wire) and, secondly, on the plug 15 via the green mnogoshtyrkovy socket behind on the device (a black/red wire) going from the ignition lock.
• At inclusion of ignition on the plug 15 tension moves. But the generator does not work yet therefore the deenergized contact of D + works as "minus". The control bulb since between tension of the onboard network receiving a power supply from the accumulator, and distinction exists tension of still not working generator lights up.
• When the engine is started and the generator reaches charging speed then the regulator of tension connects the generator to the onboard electrotechnical equipment. Now positive current arrives from the plug 15 and in addition from the D+ plug. Thanks to it there is no distinction in tension any more, the control bulb of charging dies away.
• The control bulb is not necessary for so-called "preliminary excitement" of the generator of alternating current any more, in Audi A4 it occurs already during start of the engine via the ignition lock plug 50a.

Not always there is charging

The gone-out control bulb does not prove that the accumulator is charged from the generator. It says only that there is no distinction in tension between the accumulator and the generator any more. If, for example, during the operation of the engine on single turns all consumers of current are included, the control bulb does not light up though more current of the accumulator is consumed, than can give less powerful generators: nevertheless there is no distinction in tension in comparison with the accumulator.