Ignition coil, component description (Engine 156) - GF15.10-P-2100AMG

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ENGINE 156.980 in MODEL 164, 251

ENGINE 156.982 in MODEL 209

ENGINE 156.983 in MODEL 211, 219

ENGINE 156.984 in MODEL 216, 221

Location

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

Fig 1: Identifying Ignition Coil, Component Location

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Task

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

Design (ignition coil with integrated output stage)

Fig 2: Identifying Ignition Coil With Integrated Output Stage Design

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function

An output stage is located in each ignition coil for the ignition coil primary circuit. The ME-SFI control unit (N3/10) actuates the ignition coil primary circuit between connection (2) and (4). The current flow in the primary coil (P) causes a magnetic field to form. The dwell angle control 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. The sudden collapse of the magnetic field generates the ignition voltage in the secondary coil (S), which is fed directly to the spark plugs (R4).

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

Because of the diode it is not possible to measure the resistance of the secondary coil.

For diagnosis of the ignition coils, the primary current is measured. The capacitive tap is used to connect measuring equipment.