Troubleshooting by Install
Run these on any install before diving deeper. They clear the most common causes in a couple of minutes.
The sensor only reads grain moving along its length during unloading — and it must see flow through at least the first half of the load. It reads nothing across its width, and the indicator stops recording the moment flow stops. No steady flow past the face = no reading, by design.
A wrong GRAIN type (GT560) or commodity (Libra app) is the number-one cause of readings that are “way off.” Set it to the crop you're actually running before anything else.
GT560 should power up with no errors; on the Libra window unit the black sensor's LED should be lit. Reseat the sensor connector and check the cable.
Dust is fine; a caked-over face is not. Clean it with mild soap and water.
Small or partial loads give the sensor too little grain to read — run a larger load before judging it.
Find how your sensor is mounted — each mount fails in its own way, and most fixes are about restoring even grain flow across the face.
The most common and the most forgiving mount — because you can move it. Almost every in-cart problem is solved by repositioning.
| Symptom | Likely cause | Fix |
|---|---|---|
| Moisture reads low or jumps around | Sensor sits too high above the shutter, or in a dead spot. | Reposition lower in the cart's “V” — within 18″ of the shutter, white face above the shutter edge with the shutter about ¼ open. |
| Reading quits well before the load ends | Grain flow thins over the sensor late in the unload. | Some drop-off is normal; if it stops early, lower the sensor toward the shutter where flow stays steady. |
| No reading at all | Cable pinched under the grate, or connector loose. | Reseat the connector and free the cable — route it along or under a heavy grate rail, never left unsupported. |
| Face caked / dust-covered | Grain dust or wet grain packed on the face. | Clean with mild soap and water; dust is OK, caked-over is not. |
This mount lives or dies on whether grain is pressed steadily against the door. Re-verify that before chasing anything electrical.
| Symptom | Likely cause | Fix |
|---|---|---|
| No or erratic reading | Grain isn't held consistently against the door. | Re-check the five qualifiers: auger flighting visible near the door bottom, its movement passing grain against the door, and a clean worn spot in the paint. If any answer is “no,” move to an in-cart mount. |
| Sensor struck by the auger | Mounted too low, into the flighting path. | Remount so the sensor and its hardware stay fully clear of the flighting. |
| Won't work wherever it's placed | Cupped auger or a conveyor unload. | This method needs a standard auger — switch to an in-cart or other mount. |
| Housing cracked at the bolts | Bolts overtightened. | Snug only, never overtighten — bolt heads inside the door, nuts to the outside. |
A limited-fit option for dual-auger carts only. If flow isn't constant right at the door, this mount can't be made to work — relocate.
| Symptom | Likely cause | Fix |
|---|---|---|
| Readings fall into a dead spot | Door isn't on the lowest part of the auger. | The door must sit on the lowest part of the auger, not the side; if it doesn't, this mount won't hold a reading. |
| Sensor fouls the door or moving parts | Positioned into the door swing or parts. | Reposition so it clears the door opening and every moving part. |
| Inconsistent load to load | Grain flow isn't constant at this spot. | Confirm steady flow here through the whole unload; if it isn't there, relocate the sensor. |
Grain dumps near ground level, so the sensor has to sit where grain still flows the entire dump — and these carts often have no auger to trigger AutoLog.
| Symptom | Likely cause | Fix |
|---|---|---|
| Low or erratic moisture | Grain dumps fast/uneven; sensor isn't at the constant-flow point. | Mount at the lowest point where grain flows the whole dump — inside the box by the door opening, or underneath with the supplied template. |
| AutoLog won't start on its own | No PTO or auger to trigger AutoLog. | Install the PTO sensor as a door-position sensor (FSWITCH); see the Digi-Star AutoLog manual (D3908). |
| Reading stops mid-dump | Flow moved away from the sensor. | Relocate to where grain still passes the sensor late in the dump. |
The CCS Libra Cart setup: the sensor mounts through the front window with a wireless module and its own battery, and talks to the Libra Harvest app. Most issues here are power, pairing, or the wrong commodity.
| Symptom | Likely cause | Fix |
|---|---|---|
| Black sensor LED won't light | No power reaching the sensor. | Check the cable connection, then the tractor's Aux Output fuse. Power must come from the accessory connector (Red/White wires) — not the Black/White pair, which is the tip-spout light switch. |
| Moisture reads very low | Wrong commodity type selected in the app. | In the app's field / commodity section, select the correct grain — check this first. |
| Won't pair / no water-drop icon | Bluetooth module not paired. | Re-pair in the Libra Harvest app (Add Grain Cart → check Libra + Moisture → Add; turn on smoothing). The module sits behind the front quarter panel. |
| Cuts out or unit is dead | 3.6 V lithium battery low. | Replace the 3.6 V lithium battery in the Libra unit; check battery voltage (~3.6 V) in the app's Device tab. |
| Reading won't hold calibration | Offsets not set. | Run the temperature offset, then the moisture offset (Target vs Reading) in the Device tab. |
On a wired GT560 system, two hidden codes prove whether the sensor and cable are alive.
On the Libra Cart (iPad / Bluetooth) system, work the app.
The manufacturer's own symptom → cause → fix chart (GT560 system).
| Cause | Fix |
|---|---|
| Wrong GRAIN selected | Select the correct GRAIN type |
| GRAIN type not calibrated | Calibrate for that GRAIN type |
| Sensor location problem | Change sensor position |
| Dirty moisture sensor | Clean sensor with soap & water |
| Small or partial load | Run larger loads / lower sensor position in cart |
| Sensor or cable failure | Perform Sensor Test; replace the failing part |
| Cause | Fix |
|---|---|
| Sensor location problem | Change sensor position |
| Dirty moisture sensor | Clean sensor with soap & water |
| Small or partial load | Run larger loads / lower sensor position |
| Cable unplugged or loose | Reconnect the cable |
| Sensor or cable failure | Perform Moisture Sensor Test; replace the failing part |
| Cause | Fix |
|---|---|
| Worn or loose hardware | Tighten hardware; add lock nuts; add more hardware |
Installation types, testing, calibration, and the reference table are from the Digi-Star Grain Moisture Sensor Installation & Calibration manual (GT560, D4172-EN) and the Central City Scale Libra Cart window-install and Topcon-for-Libra-Cart (M0016 / M0070) instructions. Placement guidance assumes consistent grain flow along the sensor during at least the first half of unloading.
It's usually placement — we can help you find the right spot for your cart, or test the sensor and cable.