hi , i need so help identifing the coils wiring on my mk1 oct 1.8 t 4x4 est

theres 4 wires to going to each coil pack

2 thicker ones , i assume earth and a poWer supply ? and two thiner ones

which of the thiner ones does what , ie is one a switche negative , oR a perminant neg and a switched pos from the ECU is there any wirering dia availble ? thanks

think of the coil as being just a transformer, you have two totally seperate 'sides' of the transformer, the LT side has a permanant live, and a switched earth, the HT side has a permanent earth but think of the spark plug as being the positive.... then the ecu switched the LT to earth it breaks down the magnetic field in the transformer and induces a HT current on the other side of the transformer which earths itself on the engine/cylinder head via the spark plug, hence a spark is produced... the other additional wire may not be even necessary but it acts as a shield wire to reduce RF interferance throughout the rest of the wiring loom