Is a loom without relays and fuses possible? Absolutely! It is, however, something generally only seen in higher levels of motorsport due to the cost, but products like the ECUMaster USA PMU16 are set to change this by making this technology both affordable and easy to implement. A PMU (aka PDM) replaces your conventional relays and circuit breakers, and electronically controls circuit switching and fusing current. This greatly simplifies the wiring harness, saving time, weight, and improving reliability.
If a conventional circuit breaker or fuse blows, the driver needs to physically reset it. With a PMU you can program it to wait a certain time before retrying a circuit a set number of times which can mean the difference between a DNF, a position on the leaderboard or even saving an engine in extreme cases. With easy integration to your ECU or dash via CAN bus keypads can be used to allow the driving to make adjustments on the fly and currents can be logged on each circuit which can warn when components are ready to fail adding another layer of reliability.
Want to learn more about automotive wiring? Take a look at our Wiring Fundamentals course.