APM
All alarm codes
ALARM 253

Skip Malfunction (tool setter)

Skip proxy signal at the tool setter is broken — proxy LED comes on but the signal does not arrive at the PLC. In one documented case the signal wire had fal...

Controls
T-32
Machine series
H400

Causes

  1. Skip proxy signal at the tool setter is broken — proxy LED comes on but the signal does not arrive at the PLC. In one documented case the signal wire had fallen out of a junction box partway down the loom from the tool setter.

    • sudsy55forum
      After doing a continuity test and not having any I ended up taking tool setter off completely to trace the wires. Then had to remove the way cover on the other end and found another junction box. Tested again still no co…

How to clear it

  1. 1

    Diagnose the path: machine moves tool toward setter, DECEL proxy activates and drops speed, then SKIP proxy fires to stop and the Z difference is used for tool length. If 253 fires, the SKIP signal is not reaching the PLC even though DECELERATION did. Check the SKIP proxy continuity from the proxy back through every junction box on its loom.

    • noname777forum
      the way I understand it (how it works).., machine moves tool towards tool setter, DECEL proxy is activated, machine drops the speed and moves more forward, then SKIP proxy is activated and machine stops. Current Z positi…

Confidence: medium · Single thread, but the diagnostic logic (DECEL fires + SKIP missing = check skip wiring) is solid and operator confirmed broken wire at a hidden junction box.

First sourced: 5/21/2026