About laminated harnesses

Hello.

Could you please explain more about lamination?

I think coils and injectors, which carry very periodic currents, can be a significant source of noise. If these are placed on the same layer, will it affect the signals of other sensors?

For example, if the cores of the crank angle sensor, cam angle sensor, knock sensor, etc. are made with shielded wire, and the injectors and coils are placed on the layer above that, and sensors using thin wires with weak currents, such as MAP sensors and CLT sensors, are placed on the layer above that, it would seem there would be no problem since the cores are shielded, but will the second layer not affect the third layer?

Is it better to wire the injectors and coils separately, or is it okay to integrate them?

You're 100% right that ignition and injector circuits are a high noise source and can affect other signal circuits to some degree. However, signals like the MAP sensor are low-frequency analog signals, so the effect of this noise is generally negligible in the typical automotive environment.

Crank, cam, and knock sensor signals, on the other hand, are very low voltage and low amplitude, making them extremely susceptible to the noisy environment around the engine. That’s why we always use shielded twisted pair cable for these signals; twisting helps reduce magnetic coupling, and shielding helps reduce capacitive interference.

In an ideal world, you would keep all high-noise actuator circuits away from sensitive sensor wiring, but this isn’t always practical. If you look at most factory wiring looms, actuator and sensor circuits are often routed together, with only the most vulnerable signals receiving additional protection.

Quick answer: yes, it would be better to wire them separately, but it isn’t strictly necessary. It’s very unlikely you will have issues as long as the critical signals (crank, cam, knock) are properly protected with shielding, twisted pairs, and good grounding practices.

Also, ECUs are typically designed with filtering and signal conditioning to tolerate the “normal” level of engine bay electrical noise.

Thank you. I'll try to make.