The video below gives some basic tips about how the MCU PCB and the relay PCBs should be wired up including how the large high capacity cables should be kept away from signal cables. For ease of access to wire up the relays, the MCU PCB needs to be able to tilt on one edge which is enabled by routing the signal wires through one large square aperture in the PCB on the nearest side to the rear of the machine - watch the video! It's essential to label as many of the wires as possible and keep groups of wires eg signal wires to the relays, the same colour. Something the video does not mention is that there are no connectors in the walls of the control panel, just glands. In the past, connectors were used but they take up a lot of space, make the wiring extremely messy and are prone to damage if knocked or pushed. If or when connectors are required, they will be inserted inline instead. Watching the video, one inline connector can already be seen on the engine throttle actuator as the cable supplied by the manufacturer was far too short.