Method and an apparatus for controlling glow plugs in a diesel engine, particularly for motor-vehicles

A method is provided that includes, but is not limited to the steps of driving in an on-off manner in a period of time an electronic switch in series with a respective glow plug between the terminals of a d.c. voltage supply, sensing the glow plug voltage and the glow plug current, generating analogue sense signals representative of the time integral of the glow plug voltage and current, generating analogue reference signals corresponding to the digital values of corresponding control words, comparing the sense signals to the respective reference signals and modifying the corresponding control words so as to minimize the difference between the sense signals and the reference signals, calculating the average values of the sensed voltage and current on the basis of the values of the control words at the beginning and at the end of the "on" time of the electronic switch.