Chapter 2: Fault finding – communication
12
ZP3-ECU Extinguishing Control Unit Maintenance Manual
Relay not responding
This fault is raised when the ECU double knock relay does not switch when
required. The relay is mapped as an output that is activated by a triggered input.
Indications
• The fault buzzer sounds.
• The display scrolls between two events, one showing the addressable relay
device that has not switched, the other showing the event that has triggered it
(usually a fire event). For example:
FIRE Zone 001 Dev 001 Event 001
Second Floor, Laundry Room
RELAY FAULT Zone 001 Dev 086 Event 002
• The event is printed (if a printer is configured).
• Zone in which the relay fault occurred is indicated by the appropriate red
Zone LED.
Possible causes
• The ECU double knock relay is in an isolated state.
• The ECU double knock relay is faulty.
Corrective actions
1. Press the Accept/Panel Silence button to silence the buzzer and to
acknowledge the fault.
2. If the yellow Isolated LED is on, check whether the relay is isolated. If the
relay is isolated then investigate the reasons for this. De-isolate the relay if it
is safe to do so.
3. If no other reason can be found for the fault, replace the faulty ECU main
board.
4. Reset the panel.
