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SEBU8732
before the SCR module monitor the temperatures
within the system.
Pump Electronics Tank Unit (PETU)
Alarms and Shutoff
Diesel Exhaust Fluid (DEF) Level Sensor – The
DEF level sensor monitors the volume of fluid in the
tank and signals the ECM if the level drops below a
given point.
Dosing Control Unit (DCU) – The DCU controls the
injection of the DEF and will signal the ECM if the
injection has been interrupted.
Testing
Turning the keyswitch to the ON position will check
the indicator lights on the control panel. All the
indicator lights will be illuminated for 2 seconds after
the keyswitch is operated. Replace suspect bulbs
immediately.
Refer to Troubleshooting for more information.
Selective Catalytic Reduction
Warning System
The Selective Catalytic Reduction (SCR) system is a
system used to reduce NOx emissions from the
engine. Diesel Exhaust Fluid (DEF) is pumped from
the DEF tank and is sprayed into the exhaust stream.
The DEF reacts with the SCR catalyst to reduce NOx
and leaves a nitrogen and water vapor.
NOTICE
Stopping the engine immediately after the engine has
been working under load can result in overheating of
SCR components.
Refer to the Operation and Maintenance Manual, "En-
gine Stopping" procedure to allow the engine to cool
and to prevent excessive temperatures in the turbo-
charger housing and the DEF injector.
NOTICE
Allow at least 2 minutes after shutting down the en-
gine before you turn the battery disconnect switch to
OFF. Disconnecting the battery power too soon will
prevent purging of the DEF lines after the engine is
shut down.
Note: For information on DEF, refer to this Operation
and Maintenance Manual, "Fluid Recommendations".
Selective Catalytic Reduction Warning System
Warning Strategy
The Electronic Control Module (ECM) will have either
a world-wide warning strategy or a European union
warning strategy enabled within the ECM software.
The European union warning strategy is comprised of
two different options. The two options will give
different response times for the operated to act and
different de-rates to the engine. Only one option will
be enabled.
DEF Level Warning Strategy
The DEF level world-wide warning strategy and the
DEF level European union warning strategy both offer
two options. Only one option will be enabled.
Warning Indicators
The warning indicators consist of a level gauge for
the DEF, a low-level lamp for the DEF, an emission
malfunction lamp, and the application stop lamp.
i05194082
Illustration 34
(1) DEF gauge
(A) Low-level warning lamp
Illustration 35
Emission malfunction lamp
Warning Levels
The SCR has three levels of warning. Depending on
the fault that has been detected and software enabled
will govern the time that the system will stay at each
warning level.
37
Features and Controls
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