Ignition Coil: Description and Operation
GF15.10-P-2100AMG Ignition Coil, Component Description
ENGINE 156.980 in MODEL 164, 251 up to Model Year 8
ENGINE 156.982 in MODEL 209
ENGINE 156.983 in MODEL 211, 219
ENGINE 156.984 in MODEL 216, 221 up to Model Year 8
Location
T1/1 Cylinder 1 ignition coil
T1/2 Cylinder 2 ignition coil
T1/3 Cylinder 3 ignition coil
T1/4 Cylinder 4 ignition coil
T1/5 Cylinder 5 ignition coil
T1/6 Cylinder 6 ignition coil
T1/7 Cylinder 7 ignition coil
T1/8 Cylinder 8 ignition coil
A dedicated ignition coil is plugged straight onto the spark plug (R4) for each cylinder.
Task
The ignition coils provide sufficient ignition energy under all operating conditions for the respective ignition circuit.
Design (ignition coil with integrated output stage)
1 Connection 1: Supply voltage from circuit 87 M1
2 Connection 2: Vehicle ground
3 Connection 3: Engine ground
4 Connection 4: Actuation (circuit 1) from ME-SFI control unit
R4 Spark plugs
C Capacitor
D Diode
IC Output stage
P Primary coil
R Resistor
S Secondary coil
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.