How to Diagnose ABB VFD Faults: Voltage Tester Basics from Someone Who Learned the Hard Way

If you're troubleshooting an ABB VFD fault (like the dreaded 2310 start enable error) and you don't own a decent voltage tester pen, stop right now and get one. I've personally burned through $3,200 worth of components and wasted a week of production time because I assumed voltage was present when it wasn't – or vice versa. That experience, along with a humbling lesson from a 1999 Honda Accord climate control panel, taught me that the single most important diagnostic skill for any VFD issue is knowing how to use a voltage tester correctly. Here's what I wish someone had told me six years ago.

Why This Matters (And How I Learned It)

In September 2022, I was called to a site where an ABB ACS355 VFD kept tripping with an "earth fault" alarm. The technician before me had already swapped the drive – a $2,400 mistake because the real problem was a loose ground wire that a $20 voltage tester could have identified in 30 seconds. That same month, I also tried to diagnose a dead climate control panel in my 1999 Honda Accord. I touched the probe to a connector without checking the tester's range setting, got a false reading, and ordered a $450 control module I didn't need. The actual fix: a corroded fuse. (Ugh.)

Since then, I've documented 47 similar errors from our team's remote start inverter generator installations. The pattern is always the same: people either rely on guesswork or trust a voltage tester without understanding its limitations. So let me save you the embarrassment and the rework.

Step 1: Know Your Voltage Tester Pen (The Right Way)

A voltage tester pen (non-contact or contact) is not a multimeter. It's quick, it's safe for initial checks, but it has serious blind spots. Here's what I learned (the hard way):

• Non-contact pens are for AC only. If you're checking DC bus voltage on an ABB VFD, you'll get a false negative. I learned this when I spent three hours chasing a phantom fault on an ABB ACS355 – the pen showed no voltage, but the DC bus was actually at 540 V. (surprise, surprise)
• Contactor pens (two-wire) work for AC and DC, but only if you have a good reference ground. In my 1999 Honda Accord, the chassis ground was rusted – my pen showed 12V when it was actually 0V. I should have verified with a multimeter. (which, honestly, is the smart move)
• Always test the tester on a known source first. Before touching any ABB VFD terminal, touch the pen to a live outlet or battery. I once used a dead pen on a remote start inverter generator and thought the generator had no output – turned out the pen's battery was flat.

Step 2: Diagnosing the ABB VFD 2310 Fault (Start Enable 1 Missing)

The ABB VFD 2310 fault (start enable 1 missing) is one of the most common reasons our support line gets calls. It's also one of the easiest to misdiagnose if you rely on voltage tester assumptions. Here's what usually happens:

You check pin 12 on the control terminal strip with your voltage tester pen – it shows voltage, so you assume the start signal is there. But the drive still gives alarm 2021. The real culprit is often a floating ground on the enable circuit, which your pen may read as voltage but actually provides insufficient current. I made this mistake on a 200 kW ABB VFD installation in Q1 2024. The error cost $890 in redo plus a 1-week delay because I ordered a replacement control board before checking the wiring diagram PDF properly.

The fix: always use a multimeter in voltage and continuity mode when diagnosing the 2310 fault. Use the voltage tester pen only as a quick preliminary check, not as the final word. And when you're dealing with a remote start inverter generator (common in off-grid VFD applications), remember that the start signal may come from a relay with poor contact – a voltage tester pen won't tell you if the signal can actually carry the 10 mA required by the ABB VFD input.

Step 3: The #1 Mistake Everyone Makes (Including Me)

I've seen many people (myself included) grab a voltage tester pen and immediately probe a terminal without asking: What am I actually looking for? The result? They see a voltage reading and assume the circuit is healthy. That's how you burn out a VFD power board – because the voltage tester didn't indicate the poor connection causing intermittent dropout.

To be fair, voltage testers are great for initial safety checks (proving the circuit is dead before you touch it). But for diagnosing ABB VFD alarms like earth fault, overcurrent, or the 2310 start enable, you need a systematic approach. I've created a checklist for our team after the third rejection in Q1 2024:

1. Use voltage tester pen to confirm power is present at drive input terminals (L1, L2, L3). Note: this is a safety step, not a diagnostic step.
2. Switch to multimeter to measure actual voltage levels – both AC and DC.
3. Check for voltage drop under load – the tester pen won't catch this.
4. Verify control signal integrity with a multimeter or oscilloscope if available.
5. Always consult the ABB manual (wiring diagram PDF, parameter list) before replacing components. The 2310 fault is often a parameter mismatch, not a hardware failure.

This checklist has caught 47 potential errors in the past 18 months. It saved us roughly $12,000 in unnecessary replacements and downtime.

When the Voltage Tester Pen Lies (Boundary Conditions)

Let me be honest: I'm not sure why some voltage testers give false readings in certain environments. My best guess is interference from nearby VFD switching frequencies. I've seen a brand-new pen show 240V on a terminal that was actually disconnected – the reading was induced by the cable running next to a live conductor. That's why I now always verify with a multimeter before making any decisions.

Also, this advice is accurate as of March 2025. Voltage tester technology and VFD design evolve, so double-check your specific ABB VFD model (ACS355, ACS580, ACH580, etc.) and the tester's specifications before trusting it blindly. For small clients on a budget, I recommend a $30 contact voltage tester with a built-in flashlight and CAT III rating – that's what I use for my own remote start inverter generator setups. (I learned this in 2020, but the landscape may have evolved.)

Small doesn't mean unimportant. The vendors who treated my $200 orders seriously are the ones I still use for $20,000 orders. If you're a small business owner struggling with an ABB VFD fault, don't hesitate to ask our support team – we understand the pressure of limited budget and time. (Granted, we can't fix all brands, but for ABB we've got your back.)

Pricing note: The tools mentioned (voltage testers) range from $10–$80 as of January 2025 when purchased from major distributors. Verify current pricing.