Relays depend on what your doing with the engine and what functions you need.

I cant remember what the relay was for. Probably starter inhibit.

If your running an external fan switch you don’t need that one. If you do you need the ford green 5 pin relay as it won’t work otherwise for some reason.

Start inhibit stops the engine from cranking as part of the Immobilizer. If your not fussed it works perfectly well with out.

Power control relay., again it depends on what your putting it in. If you where using heavy duty switch gear you could do with out that as well. If your sticking it back in a car I would use it.

I will say the St170 is one of the most involved looms I’ve done due to the amount of sensors and actuators.


just do one circuit at a time and work through it. I often do the injectors first. Four switched earths to the ecu and one switched live.
Simples.
Coil, two switched earths to the ecu and one switched live

And so on.....