How to Test a Load Cell (and When to Replace It)

Updated November 9, 2026

The short answer: you can test a load cell with a good digital multimeter in four checks: look it over for damage, measure the zero balance (signal output with no load), measure the bridge resistances with the power off, and check insulation resistance between the wires and the cell body. Compare every reading to the cell's data sheet. A cell that fails any of these, or won't return to zero after a load, is usually the one to replace. In a multi-cell scale, you find it by testing each cell on its own at the junction box.

Signs of a bad load cell

• The scale won't zero, or the zero drifts during the day.
• Readings jump around or creep up or down with a steady load on the deck.
• One corner reads differently from the others (a failed corner test).
• The indicator shows an over-range or under-range error with nothing on the scale.
• The trouble started after an overload, a dropped load, a lightning storm or a flood.

Before you start, rule out the simple causes: debris under the deck, something touching the platform, a damaged cable or a wet junction box.

Tools you need

• A digital multimeter that reads millivolts and ohms accurately.
• The load cell data sheet (rated output in mV/V, input and output resistance, zero balance tolerance).
• For insulation testing, a low-voltage insulation tester. Many manufacturers say not to exceed 50 V DC on a load cell.
• The wiring color code for your cell. Our load cell wiring guide lists the common ones.

How to test a load cell: 5 checks

1. Visual inspection

Look for a bent or cracked body, corrosion, a damaged or crushed cable, a torn boot on the gauge area, and loose mounting hardware. A deformed cell has been overloaded and won't come back.

2. Zero balance

With the scale empty and the cell powered by the indicator, measure the voltage between +signal and –signal. Divide it by the excitation voltage to get mV/V and compare to the zero balance tolerance on the data sheet (often around ±1% of rated output). A reading well outside the tolerance usually means the cell has been overloaded or shock-loaded.

3. Bridge resistance

Power off and disconnect the cell. Measure resistance across +excitation and –excitation (input), then across +signal and –signal (output), and compare both to the data sheet. Then measure each signal lead to each excitation lead; the readings should be close to each other. An open circuit, a short, or an unbalanced pair points to internal damage or moisture.

4. Insulation resistance

With the cell disconnected, tie all its leads together and measure to the cell body and to the cable shield. A healthy cell reads extremely high resistance. A low reading means moisture has got in, which is the most common failure in washdown and outdoor scales.

5. Load and return-to-zero

Put a known weight on the scale, then take it off. A good cell reads the weight steadily and returns to zero. If the reading creeps or zero shifts after each load, the cell is suspect.

Finding the bad cell in a multi-cell scale

Floor, tank and truck scales have several cells summed in a junction box. Disconnect all but one cell (or use the box's jumpers), and repeat the zero and load checks cell by cell. You can also place the same test weight over each corner in turn; the corner that reads differently, or drifts, leads you to the cell. Digital diagnostic junction boxes do this automatically.

Replacing a load cell: what to match

• Type and mounting: shear beam, S-beam, single point, canister or double-ended beam, with the same mounting holes and thread.
• Capacity: the same rated capacity as the cells already in the scale.
• Rated output: the same mV/V so the trimming still works.
• Environment: stainless and hermetically sealed for washdown, alloy steel for dry areas.
• Cable length and color code.

Common replacements we stock include the GX-1 shear beam load cell for platform and floor scales (from $115 at the time of writing, November 2026), the SL-818 5,000 lb shear beam kit (from $115) and the Rice Lake RL20000ST stainless S-beam. Check the product page for the current price. Browse every option in load cells, Rice Lake load cells and load cell kits.

Detailed test procedures and tolerances are in Rice Lake's Load Cell and Weigh Module Handbook.

Safety and legal-for-trade

This is general guidance. Lifting a platform or vessel to reach a cell is heavy, hazardous work, and a replacement cell means re-trimming and recalibrating the scale. Use a qualified scale technician. If the scale is legal-for-trade, check with your state weights and measures office; most states expect the scale to be placed back in service by a registered service company.

Load cell testing FAQs

Can you test a load cell with a multimeter?

Yes. A multimeter covers zero balance and bridge resistance checks. Insulation resistance needs a low-voltage insulation tester.

What should a load cell read with no load?

Close to zero millivolts, within the zero balance tolerance on its data sheet. A large offset usually means the cell has been overloaded.

Do I have to replace all the load cells if one fails?

Not always. If the cells are the same model and the rest test good, replacing one and re-trimming the scale is common. Older scales with several weak cells are often better off with a full set.

What causes load cells to fail?

Overload and shock loading, moisture getting into the cell or cable, lightning and welding currents, and cable damage are the usual causes.

Need a replacement load cell?

Send us the make, model and capacity printed on the cell's label, or a photo of it, and we'll match it. Call SellEton Scales at (844) 735-5386 or send us a message. For routine care, see our scale maintenance tips.