1LS / 2LS Check Negative

What does >LS-FAULT ! mean?

This blinking event message indicates that the safety check for Limit Switch 1 (1LS) or Limit Switch 2 (2LS) has failed, blocking elevator operation. This fault implies a critical issue with the limit switch integrity or its monitoring circuit on the OTIS 2000 Controllers MCS120/MCS220.

• Malfunction of Limit Switch 1 (1LS) or Limit Switch 2 (2LS).
• Incorrect wiring or poor connection to 1LS or 2LS.
• Mechanical damage or misalignment of the limit switches.
• Fault in the LCB_II control system's monitoring of limit switches.

Click steps to track your progress.

1. 1

   Inspect Limit Switch 1 (1LS) and Limit Switch 2 (2LS) for physical damage, obstruction, or misalignment.

2. 2

   Verify electrical connections to both 1LS and 2LS for continuity and proper termination.

3. 3

   Measure the voltage across the 1LS and 2LS terminals in both actuated and non-actuated states, comparing with expected values.

4. 4

   If accessible, manually actuate each limit switch to confirm its switching action.