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Dominator Inputs and single sensor ground

EFI Wiring Fundamentals

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Hey guys, I'm looking to terminate much of J2A for future use as possible. Thinking of using DTM 12 pin connectors to achieve this and 22 AWG TXL

My plan is to use this repeating pattern:

Pin 1 = Signal 1, Pin 2 = +5V 1, Pin 3 = Sensor Ground 1, Pin 4 = Signal 2, Pin 5 = +5V 2, Pin 6 = Sensor Ground 2, Pin 7 = Signal 3 Pin 8 = +5V 3, Pin 9 = Sensor Ground 3, Pin 10 = Signal 4, Pin 11 = +5V 4, Pin 12 = Sensor Ground 4.

This ends up with (20) +5 pins and sensor ground pins, reserving frequency for a 6th plug. My question is, what is the best way to branch 20 wires off of 1 wire? Or is the answer the obvious one? Crimp 21 wires into 1 open butt connector, not sure if there is even a size out there that could accommodate this load.

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Hey Jesse,

A future-proof “spares” connector is always a great idea, I almost always include one when building a new harness.

That said, I’d simplify your approach a bit. Having a dedicated 5V and sensor ground for every spare input will quickly add unnecessary bulk and complexity. Instead, I’d recommend running a single 20 AWG 5V and sensor ground to each spare connector.

Using 12-pin DTM connectors, you can still achieve 20 spare inputs across just two connectors. This also means you’re only splicing your 5V and sensor ground into two branches instead of 20, which is far more manageable.

My reasoning for this, in reality, you’re unlikely to use all your spare inputs later, typically it’s only 3–4 additions. With this setup, you can build a small sub-harness from the spare connector and branch your 5V and ground locally (down to 22 AWG if needed) for the added sensors. I've attached a quick example.

If you expand again later, you’ve still got the second spare connector available. And worst case, adding another splice into the existing 5V and ground isn’t difficult.

It’s great to plan ahead, but it’s also easy to overdo it and add complexity that may never be used.

On your question about combining 20+ conductors into one, from a current standpoint, it’s not an issue. Most sensors draw very little current, typically in the milliamps. For example, a typical 5V pressure sensor might draw ~20 mA. Even with 20 sensors, that’s only 0.4 A total, which is well within the capacity of a 20 AWG (and even 22 AWG) conductor.

Because of that, you can confidently run a single 20 or 22 AWG 5V and sensor ground feed, and then splice multiple branches from it to supply your sensors. In practice, that single feed could support well over 20 sensors if needed, so you’re nowhere near the limits here.

Hope this is helpful for you.

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