Data Cables & Pinout¶
Overview¶
The four RJ45 jacks are arranged as two dual-jack connectors — RJ5 (left) and RJ3 (right). Each jack gets its own Cat6 ethernet cable, cut from a standard patch cable — purchasing details are on the Unboxing page.
All left/right port names in this documentation mean as you face the connector openings, exactly as in the photo above.
Wire colors in this documentation follow the T568B Cat6 standard — the wiring used by almost all factory-made patch cables, including the CableWholesale cables we recommend. Pin numbering is 1–8 per jack. The complete pinout for all four cables:
Confirm wire colors against your actual cable — never trust color alone
Patch cables are wired to one of two color standards, and cheap cables may follow neither:
- T568B (this documentation) — the common factory default. Roughly 90% of patch cables in the US are wired T568B, so this is almost certainly what you have.
- T568A — an older/alternate standard that swaps the orange and green pairs. On a T568A cable the colors at pins 1, 2, 3, and 6 differ from the diagram above (the blue and brown pairs are the same on both). If your cable is T568A, use the T568A color map (separate page).
- Non-standard cables — some budget cables only guarantee end-to-end continuity and use arbitrary internal colors.
The signal on each pin is set by the regulator's jack — the wire color is only a label to help you find the right conductor. Always confirm by pin position at the plug, not by color. To read pin 1: hold the RJ45 plug with the gold contacts facing you and the cable pointing up (locking tab at the back) — pin 1 is the leftmost contact, pin 8 the rightmost. If pin 1 is orange/white the cable is T568B (this documentation); if pin 1 is green/white it is T568A.
This matters because a 12 V signal on the wrong pin can destroy the board. For example, the solid orange wire is the 5 V output (pin 2) on a T568B cable but the IGNITION input (pin 6) on a T568A cable — putting your ignition 12 V on the wrong one back-feeds the 5 V rail and damages the regulator.
Use dielectric grease on assembly
Put a small amount of dielectric grease in each RJ45 jack before plugging the cable in, and on the power terminals. It displaces moisture, slows corrosion on the contacts, and does not interfere with the connection — the mating pressure pushes it aside where metal meets metal. The board itself is conformally coated and resists splash; greased connectors are what closes the remaining path.
Picking the right cable¶
Two separate cable properties decide which signal lands on which wire: the color standard (T568B vs T568A — see the warning above) and the wiring type (below). Get both right before you cut a cable.
Wiring type — use straight-through, not crossover¶
Use a straight-through cable, where pin 1 at one end connects to pin 1 at the other, pin 2 to pin 2, and so on. Avoid a crossover cable, which deliberately swaps the orange and green pairs between its two ends — so the wire that carries a given signal is different depending on which end you cut from, and one half of the cable will not match this documentation.
Crossover cables are largely obsolete (modern network gear self-corrects with Auto-MDIX, so they are rarely needed anymore) but they are still sold and still turn up in parts bins and old kits, so confirm you have a straight-through cable before cutting. The simplest check: hold both RJ45 plugs side by side, contacts toward you — on a straight-through cable the eight colors appear in the same left-to-right order on both ends; on a crossover they do not.
Have a T568A cable (pin 1 green/white)? The full T568A pinout is on the T568A Cable Color Map page.
Next step¶
With the cables terminated, mount and wire the sensors: Current Sensor and Temperature Sensor.