Checking Ignition Coil (Primary Coil)

Checking ignition coil (primary coil) (M43, M44)







Circuit diagram of compact ignition coil in breakerless ignition distribution system:
3 Terminal 4a: joint ground of secondary coils to DME control unit
2 Terminal 15
5 Terminal 1 of ignition coil 4
7 Terminal 1 of ignition coil 3
6 Terminal 1 of ignition coil 2
1 Terminal 1 of ignition coil 1
4 Terminal 4 High voltage to spark plug







Multimeter Test:
Resistance of primary coils ....... 0.8 ohms
Measurements of primary connection between:
- Pin 1/pin 2 (terminal 1/15)
- Pin 6/pin 2 (terminal 1/15)
- Pin 7/pin 2 (terminal 1/15)
- Pin 5/pin 2 (terminal 1/15)
Resistance of the secondary coil cannot be measured







Pin assignment, primary connection
- Pin 1 terminal 1 of ignition coil 1
- Pin 2 = terminal 15
- Pin 3 = terminal 4a
- Pin 4 = not allocated
- Pin 5 = terminal 1 of ignition coil 4
- Pin 6 = terminal 1 of ignition coil 2
- Pin 7 = terminal 1 of ignition coil 3







Check casting compound of coil carrier for hairline cracks.
If the gray material has emerged at the edges of the coil carrier, this indicates a faulty ignition output stage in the DME control unit.
Replace ignition coil.
Check DME control unit.
Additional notes on checking: refer to Checking Ignition Coils (Secondary Coil) using test adapter kit 12 7 040.