ST3400 · 408000 Control Box
The scale head. Holds the preset (target) weight; its START/STOP key runs the dispense and triggers the auto cut-off. Full operation is in Digi-Star manual D3943.
Under the tender frame or hopper — they tell the ST3400 how much seed has been delivered.
The relay box that switches the tender's own seed control. 12 V only, 10 A internal limit, with a MANUAL / AUTO toggle on top. Built for on/off style controls.
ORANGE, BLUE, RED, BLACK — the only four wires you land. Colors and destinations are in the table below.
The tender's existing dispense control. The 408000 splices in-line with it so both hand and auto control still work.
Battery / key-switch / fused 12 V to RED, ground to BLACK.
MANUAL passes the button/remote straight through; AUTO hands control to the scale.
The 408000 is 12 V only and internally limited to 10 A. It splices into the small control signal — never the motor's high-current path.
The 408000 works with two on/off seed controls: a pull solenoid (throttle-cable) or a hydraulic forward solenoid (“AUGER FWD” / “Forward Solenoid”), triggered by a spout button or remote. Variable-rate throttle or door open/close systems may need a different control box — check this before you buy or wire. If it's “other or unknown,” call us or Digi-Star first.
Bolt or screw the 408000 by its tabs within about 2 feet of the ST3400 so the cable reaches without stretching, out of the weather and clear of moving parts.
Follow the wire table below for your control type. Only four wires connect — ORANGE and BLUE splice into the tender's existing control circuit; RED and BLACK are power and ground.
Set the switch to MANUAL and press the spout button / remote — the solenoid should activate and dispense. Then turn the auger/conveyor off.
Set the switch to AUTO, turn on the ST3400, and press START/STOP — the solenoid should activate. That confirms the auto path. Set a preset and run a test load; tune the preset for coast so the delivered weight lands on the number.
The same four wires, landed differently for a pull-solenoid vs. a hydraulic control. ORANGE and BLUE go where the button/remote wire used to be; RED and BLACK are power and ground.
| Wire | Pull Solenoid (throttle cable) | Hydraulic (forward solenoid) |
|---|---|---|
| ORANGE | The relay's small ‘switch’ terminal (after removing the button/remote wire from it) | The (+) terminal / short wire at the forward solenoid |
| BLUE | The loose wire(s) you removed — from the spout button / remote | Same — the loose button / remote wire(s) |
| RED | Battery +12 V, key switch, or fused link | Battery +12 V, key switch, or fused link |
| BLACK | Negative / ground | Negative / ground |
Most calls are the MANUAL/AUTO switch, a missing preset, or ORANGE/BLUE landed wrong.
| Symptom | Likely cause | Fix |
|---|---|---|
| Won't cut off at the target | Box left in MANUAL, or no preset set. | Set the switch to AUTO and enter a target weight on the ST3400; MANUAL bypasses the auto cut-off. |
| START/STOP does nothing in AUTO | ST3400 off / unpowered, or RED-BLACK not landed. | Confirm the ST3400 powers up with no errors; check RED to +12 V and BLACK to ground (the ST3400 has internal fuses too). |
| Won't dispense even in MANUAL | BLUE not tied to the button/remote wire, or box unpowered. | Recheck the BLUE splice to the loose button/remote wire and the RED/BLACK power. |
| Dispenses but never stops | Variable-rate throttle or door open/close control. | The 408000 is for on/off controls only — a variable-throttle or door system may need a different control box. Confirm the control type. |
| Hydraulic: wrong function switches | ORANGE landed on the wrong solenoid. | With a volt meter, find the wire that reads +12 V only when dispensing (the ‘forward’ solenoid) and land ORANGE on its (+). |
| Trips / won't carry the load | Draw exceeds the box's 10 A limit. | The 408000 is internally limited to 10 A and 12 V — it switches the small control signal, not the motor's high-current path. Keep it on the ‘switch’/solenoid side. |
| Intermittent operation | Loose butt splice or poor ground. | Redo the ORANGE/BLUE splices with insulated connectors; verify BLACK is on clean frame ground. |
| No weight on the ST3400 | Load cell or cable problem. | Reseat the cell connectors and check the cable; see the Cables & Pin-Outs page. |
Wire colors, control types, the 10 A / 12 V limit, and the MANUAL/AUTO test procedure are from Digi-Star manual D3967 Rev A (408000 Control Box Installation for the Seed Tracker ST3400). Variable-rate throttle or door open/close systems may require a different control box — confirm the control type before installing.
Tell us the tender and how it dispenses (pull solenoid, hydraulic, or something else) — we'll match the control box and walk the wiring.