Junction Box Wiring & Color Codes (Weigh-Tronix vs Digi-Star)

In a spring-loaded junction box, the two sides follow different color codes: the indicator side follows the Digi-Star code, and the weigh-bar side follows the Weigh-Tronix code. Mixing them up is the most common wiring mistake. On a five-weigh-bar unit, one port is doubled to take the extra bar.

Weigh-Tronix — weigh-bar side

• + Excitation: Green

• − Excitation: Black

• + Signal: White

• − Signal: Red

• Ground: Bare / Orange

Digi-Star — indicator side

• + Excitation: Red

• − Excitation: Black

• + Signal: White

• − Signal: Green

• Ground: Bare / Orange

The catch: Weigh-Tronix uses green for +Excitation and red for −Signal, while Digi-Star uses red for +Excitation and green for −Signal. Black, white, and bare/orange are the same on both — that green/red flip is what catches people.

Process-of-elimination testing

• If you can, unbolt the junction box and lay it flat for easier access to the leads.

• Disconnect all but one of the weigh-bar / load-cell cables at the box.

• Zero the indicator and watch what happens after pressing zero.

• Work through the bars one at a time to find the faulty one.

Need parts or a hand? We build and repair junction boxes, summing boards, and bars for any brand — call 800-582-3175.