Describing Engine Gauge Panel; Dual Ecm Automatic Switching - Clarke C18H Instruction Manual

2.6.3 Describing Engine Gauge Panel

2.6.3.1 ECM Selector Switch and Primary/Alternate
ECM
Clarke UL/FM Engines come equipped with dual
ECMs and an ECM Selector Switch on engine gauge
panel. (Item #6). Default position of ECM selector
switch is to the Primary ECM.
failure of the Primary ECM, where-by the engine shuts
down or will not start, it will become necessary to
manually switch to the Alternate ECM position. When
the ECM Selector Switch is positioned to the Alternate
ECM position a warning light will illuminate at the
engine gauge panel. Also, the main controller will
display a warning light and an audible alarm. The
engine should then be re-started manually.
section 2.6.1). Contact a Clarke Authorized Service
Dealer immediately when this situation occurs to
troubleshoot. (See section 7.0).
Information displayed on the PowerView diagnostic
gauge will come from either the Primary or Alternate
ECM depending upon the position of the ECM
Selector Switch.
If a fault code(s) is displayed and comes from the
Primary ECM, and then the ECM selector switch is
moved to the Alternate ECM position, it may be
necessary to "crank" the engine for the Alternate ECM
to pick-up the same fault code(s).

2.6.3.2 Dual ECM Automatic Switching

Engine models utilizing dual ECMs are equipped with
a BASE unit (Board for Auto-Switching ECMs) that
can detect failure on either primary or alternate ECM.
The BASE monitors two separate heartbeat signals
from each of the ECMs. If the BASE fails to detect
BOTH of these signals, the BASE will recognize this
as an ECM failure and initiate the automatic ECM
switching process. If the BASE fails to detect only one
of these signals, the automatic ECM switching process
will not initiate however an indication will be made by
a green status LED on the BASE.

Normal Operation: LED Flashes at 1/10 Hz or
1 time in 10 seconds

Primary heartbeat failure only: Led Flashes at
½ Hz or 5 times in 10 seconds.

Secondary heartbeat failure only: LED Flashes
at 1 ½ Hz or 15 times in 10 seconds.
In the event of a
(See
18
BASE &
green status
LED
Interior view of engine gauge panel door - BASE
dual ECM auto-switching device and green LED
Figure #9A
If the currently selected ECM experiences a failure
detected by the BASE unit, an ECM warning alarm
will be sent to the fire pump controller via interconnect
terminal 303, and will automatically switch to the other
functional ECM. If the automatic switching devices
switches to alternate ECM, a visual indication light
will illuminate on the engine control panel, and an
alternate ECM alarm will be sent to the fire pump
controller via interconnect terminal 301. Upon failure
of the second ECM, the automatic switching device
will alarm an ECM failure alarm to the fire pump
controller via interconnect terminal 304. Additionally,
the BASE status LED will flash at rate of 2 ½ Hz or 25
times in 10 seconds.
If an ECM failure occurs during engine operation, the
automatic switching device will control engine
shutdown and will prevent starter motor re-engagement
while the engine is shutting down. After the engine
safely comes to a stop the automatic switching device
will switch to the other functional ECM and will then
allow starter motor re-engagement control from the fire
pump controller.
The automatic ECM switching process will not initiate
upon failure of any primary, alternate, or non-critical
engine sensors as per UL/FM.
After ECM repair, activate the ECM Failure reset
switch to the down position for 3 seconds and release.
This will de-activate the ECM Warning and Failure
alarms to the fire pump controller at interconnect
terminals 303 and 304.
The hand operated ECM selector switch allows for
manual selection of either primary or alternate ECM.
In the event of failure of the BASE unit while the
ECMs are functional, a Diagnostic Trouble Code of