EL
ErrorLib
Brands
||
  1. Home
  2. Mitsubishi Electric
  3. MELSEC iQ-R I/O Module
  4. 2003H
About·Privacy·Terms

ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

2003H

Output dark test error

Mitsubishi Electric · MELSEC iQ-R I/O Module

What does 2003H mean?

During an output dark test, the expected test pulses were not detected. This signifies that the output circuit did not respond correctly to a diagnostic test, potentially due to wiring faults, issues with connected devices, or an internal hardware problem.

Common Causes

  • An unused output terminal is not configured with 'Not used' in 'Wiring output selection'.
  • Faulty connected devices or incorrect wiring on the output terminal.
  • Influence from electrical noise affecting the output dark test pulses.
  • An internal hardware error within the I/O module with diagnostic functions.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    For any unused output terminals, ensure 'Not used' is selected for 'Wiring output selection'.

  2. 2

    Identify the specific terminal experiencing the error using 'Output dark test error detection state' (Un\G1540), then inspect and adjust connected devices and wiring.

  3. 3

    Implement measures to mitigate electrical noise, such as shielding cables or isolating power supplies.

  4. 4

    If the error persists after noise mitigation, the module may require replacement due to a hardware failure.

Browse all codes in this manual (56)
Verified technical data. Last updated: April 2026

Related Faults

00A12HFailure of Disabling Safety Module1000HPower Shutoff1100HTransmission Interval Monitoring Time Range Error
Source: Mitsubishi Electric MELSEC iQ-R I/O Module
Open Manual (Page 203)Search more codes in this manual