Component description for ignition coils - GF15.10-P-2100CY

ENGINE 272.911 in MODEL 204.0 up to Model Year 8

ENGINE 272.921 in MODEL 204.0/2 up to Model Year 8

ENGINE 272.947 in MODEL 204.0/2 up to Model Year 8

ENGINE 272.948 in MODEL 204.0 up to Model Year 8

ENGINE 272.961 in MODEL 204.0/2 up to Model Year 8

ENGINE 272.971 in MODEL 204.0 up to Model Year 8

Location

An ignition coil (dedicated ignition coil) is plugged directly onto the spark plug (R4) for each cylinder.

Fig 1: Identifying Ignition Coils

Courtesy of MERCEDES-BENZ USA

Fig 2: Identifying Ignition Coil Design

Courtesy of MERCEDES-BENZ USA

Task

The ignition coils provide sufficient ignition energy under all operating conditions for the respective cylinder.

Design

The ignition output stages are integrated into the ignition coils.

Fig 3: Identifying Ignition Coil Function Diagram

Courtesy of MERCEDES-BENZ USA

Function

The ME-SFI [ME] control unit (N3/10) actuates the respective ignition coil at "circuit 1". The ignition output stage reacts by closing the primary circuit at the ground end. The current flow in the primary coil causes a magnetic field to form. The dwell angle control in the ME-SFI [ME] control unit determines the operating time of the ignition coil primary circuit and thus the magnetic saturation of the ferrous core of the ignition coil. The primary current flow is interrupted at the moment of ignition timing point.

Due to sudden collapse of the magnetic field in the primary coil, the ignition voltage is induced in the secondary coil (generated).

The ignition voltage reaches the spark plug via the resistor and high-voltage terminal.

The diode is fitted to suppress an additional ignition spark when the primary current is switched on.

The power supply to the ignition coil comes via "circuit 87 M1".

Diagnosis

Because of the diode it is not possible to measure the resistance of the secondary coil. In order to diagnosis Ignition coils the primary current is measured via the capacitive pick up.