What the 1002 alarm means

The controller is ready but the drives-on command has not been given, so $DRIVES_ON is false and no axis can move. In T1/T2 the enabling switch must be held; in AUT the external drives-on input must be asserted. This fault appears in a large share of our KUKA KRC2 / KRC4 / KRC5 (KSS) service tickets, and the first round of on-site checks usually finds the source.

Most common causes

  • Enabling switch on the SmartPad not pressed or only half-pressed
  • External drives-on button or PLC input not asserted in AUT mode
  • A pending safety message is blocking the drives-on command
  • Contactor or drive chain fault preventing drives-on from completing
Field note: Most of the time the problem is the first item on the list, so ruling it out saves you half the time.

Step-by-step field fix

  1. In manual mode, press the enabling switch to the middle position and request drives on
  2. In AUT mode, verify the external drives-on input is asserted and mapped correctly
  3. Clear all pending messages, then request drives on again
  4. Listen for contactor closure; if absent, diagnose the drive power chain
  5. Check the event log for the stop reason that opened the drives-on circuit
Safety first: For KUKA 1002, this alarm is the safety circuit itself: jumpering a door switch or forcing a contactor removes the protection entirely - no protective action when something happens, and no defensible account of responsibility. On site you may look at after confirming power-off the first step yourself: In manual mode, press the enabling switch to the middle position and request drives on. Beyond that it is the e-stop chain and safety circuit work - leave it to a professional.

How we diagnose safety-chain faults on site

KUKA 1002 belongs to the safety chain & e-stop family. On KUKA 1002 the failing stage is SIB safety input board / SafeOperation option on the KRC2 / KRC4 / KRC5 - continuity of one series loop: e-stop buttons, door switches, light curtains, safety relays and the enabling device. We start reading KUKA 1002 at the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs.

The chain involved in KUKA 1002 runs: e-stop / door / curtain -> safety relay (dual channel) -> controller safety input -> motor-off and brake apply.

On KUKA 1002 the field usually reports Enabling switch on the SmartPad not pressed or only half-pressed, but the check that matters is not continuity: The point of a safety loop is not whether it conducts but whether both channels conduct together. The relay compares channels; if one opens tens of milliseconds early it latches as a channel fault. The commonest causes are plain: oxidised door-switch contacts raising contact resistance, or one loose terminal. We measure segment by segment - pendant e-stop, panel e-stop, external e-stop, safety door - and lock onto whichever segment reads differently on the two channels.

Field notes on this page cover KUKA 1002 (Drives-On Not Asserted ($DRIVES_ON)); written by the Henghuan repair team, updated 2026-10-01.

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Related Safety Chain & E-Stop alarms

1001 — Operator Safety Acknowledgment Required 1010 — Move Enable Missing — E-Stop or Safety Relay Open 15074 — Safety Junction Error in Drive — Channel N
Same family: this code belongs to the Safety chain & e-stop alarms family - the page collects all Safety chain & e-stop-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for ABB · Yaskawa · Universal Robots and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the KUKA 1002 alarm mean?

The controller is ready but the drives-on command has not been given, so $DRIVES_ON is false and no axis can move. In T1/T2 the enabling switch must be held; in AUT the external drives-on input must be asserted. This fault appears in a large share of our KUKA KRC2 / KRC4 / KRC5 (KSS) service tickets, and the first round of on-site checks usually finds the source. KUKA 1002 sits in the safety chain & e-stop family; on our work orders the highest-frequency trigger for this code is "Enabling switch on the SmartPad not pressed or only half-pressed".

QCan I clear a KUKA 1002 alarm myself?

Whether KUKA 1002 clears on its own depends on the outcome of "In manual mode, press the enabling switch to the middle position and request drives on". Finish the flow with "Check the event log for the stop reason that opened the drives-on circuit" to confirm KUKA 1002 - do not skip it. If that step is clean, the second most frequent cause on KUKA 1002 is "External drives-on button or PLC input not asserted in AUT mode". Do not chase takt through a repeating KUKA 1002. Left alone, safety chain & e-stop faults tend to graduate from repairable to must-replace.

QA safety-chain fault like KUKA 1002 stops the line - how fast can you be here?

The commonest causes we see on KUKA 1002 are "Enabling switch on the SmartPad not pressed or only half-pressed, External drives-on button or PLC input not asserted in AUT mode, A pending safety message is blocking the drives-on command", so we stock the van against those. For KUKA 1002 specifically, we stock along the loop: safety relays, common door switches, e-stop buttons, light-curtain pairs and terminal blocks. For KUKA 1002, a safety-chain fault stops the whole line, so we rank it top priority and pre-triage by phone: door switch, e-stop or relay. Before we roll, tell us what KUKA 1002 shows on the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs and what the machine was doing - phone or video triage is free.

The notes on KUKA 1002 were summarized by the Henghuan Robotics repair team from on-site service. The alarm interpretation is our empirical summary for troubleshooting reference and may vary by controller and software version — please check KUKA documentation or contact us with questions. Henghuan is an independent service provider, not affiliated with or endorsed by KUKA.