EL
ErrorLib
Brands
||
  1. Home
  2. Otis
  3. DSD 412 DC Elevator Drive
  4. 902
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.

902

POWER SUPPLY FAULT

Otis · DSD 412 DC Elevator Drive

What does 902 mean?

The Low Voltage Power Supply (A4) output has dropped below 60% of its rated voltage, leading to a drive shutdown. A CPU Reset is required after the cause of the fault has been rectified.

Common Causes

  • Loss of 115V AC input power to the A4 power supply.
  • Short circuits present in the +5V, +/-15V, or +24V circuits, potentially external to the drive itself.
  • Failure of the A4 Power Supply module.
  • A blown fuse located internally within the A4 power supply.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the presence of 115V AC input power to the A4 board.

  2. 2

    Check for short circuits in the +5V, +/-15V, and +24V circuits, inspecting both internal and external connections.

  3. 3

    Inspect any internal fuses of the A4 power supply for continuity and replace if blown.

  4. 4

    If all other causes are ruled out, replace the A4 Power Supply PCB.

  5. 5

    Perform a CPU reset on the Drive Control PCB after addressing the fault.

Browse all codes in this manual (48)
Verified technical data. Last updated: April 2026

Related Faults

117/118SERIAL COMMUNICATION FAULT400MOTOR OVERLOAD FAULT401EXCESSIVE FIELD CURRENT
Source: Otis DSD 412 DC Elevator Drive
Open Manual (Page 84)Search more codes in this manual