17
Describing Engine Instrument Panel
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. In the event of a 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. (See section 3.2.1). Contact a Clarke
Authorized Service Dealer immediately when this situation occurs to troubleshoot. (See section 10.0).
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).
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.
Double ECM failure: LED Flashes at 2 ½ Hz or 25 times in 10 seconds.
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 SPN 2145 FMI 9 will be
displayed on the diagnostic gauge.
Programming ECM with Automatic Switching Device
This procedure will be performed by Clarke Certified Service Dealer or a Cat Dealer.
In the event of a failed or damaged ECM, programming will be required on the replacement unit. The
diagnostic tool will be connected to the Service Tool Connector (#10 in Figure #8). In addition to the typical
programming procedure used on Caterpillar engines, some extra steps are required.
To program the Primary ECM:
In manual operation mode, select the Primary ECM with the ECM SELECTOR (Item #4 on Figure #3-1).
Unplug the BASE dual ECM auto-switching device on the back side of the engine gauge panel door.
(See Figure #3-4.)
This will prevent the BASE from switching to Alternate ECM during the software re-flashing process.
Complete the programming process as normal.
Plug the BASE back in.
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