Note: On certain applications and in low ambient
temperatures, a portion of the radiator may need to
be blocked to increase engine temperatures to a safe
level for the test to complete.
Once the target SCR inlet temperature has been
achieved and the NOx conversion level has been
met, the test will complete successfully.
If a related diagnostic code is generated during the
test, the test will be aborted.
If the test times out with no active codes and NOx
conversion test criteria is not met, a low NOx
conversion error identifier is logged.
If certain DCU faults are active, the test will cycle
power to the DCU in an attempt to clear these faults
before continuing the test.
If an active low DEF concentration event or low NOx
conversion ratio event is present, the test will be
modified. This mode will request that DEF dosing be
reduced to a minimum to remove all stored ammonia
in the catalyst. The test will then attempt to clear the
NOx conversion and DEF concentration events in an
abbreviated time period. If the events are cleared, the
test will complete successfully. If the events are still
active, the test will fail after a timeout period.
Manual Hydrocarbon Dosing Capability
Test
Avoid contact with hot surfaces. Exhaust piping
and engine components become hot during en-
gine operation and cool slowly after engine shut-
down. Any contact with hot surfaces can cause
severe burns.
This test is used to check the HC dosing process.
Periodic HC dosing elevates the exhaust gas
temperature to clean the SCR system so that
acceptable NOx conversion is maintained. The test
checks that HC dosing raises the SCR intake
temperature to the correct level.
The test must be performed at low engine speed and
low load. The test will only start when all the following
criteria are met:
• The engine is running
• Coolant at the minimum required temperature
• No active diagnostic codes
The test will initially use the EBPR to increase the
DOC intake temperature. When the target DOC inlet
temperature is reached, HC dosing will begin and the
initial temperature rise across the DOC is assessed.
If the temperature rise is insufficient, the EBPR will
be used to raise the DOC intake temperature further.
If the required temperature rise is achieved, HC
dosing will increase until the DPF intake temperature
reaches approximately 475° C (887° F). If the target
temperature is achieved, HC dosing continues until
the SCR intake temperature reaches 475° C
(887° F). If the target SCR intake temperature is
achieved, the test will end successfully.
Diagnostic Tests Listed in the Diesel
Exhaust Fluid Controller Menu
DEF Dosing System Purge Test
This test verifies that the DEF purging process is
working correctly by purging the DEF pump and
lines.
The DEF System places the pump into reverse
operation. The DEF is pumped from the injector back
into the tank. This process de-pressurizes the system
and empties the DEF lines prior to maintenance
being performed.
DEF Dosing System Accuracy Test
This test is used to measure the amount of DEF that
the dosing system is spraying into the exhaust
system. The test can also be used to verify that there
is an acceptable spray pattern from the DEF Injector.
Note: The DEF injector must be removed from the
exhaust system during this test and placed in an
appropriate container. Failure to do so could result in
issues with the SCR system operation.
This test turns on the DEF pump and injects DEF for
6 minutes. The DEF injector atomizes the DEF and
the spray pattern must be uniform in order for the
SCR system to work properly. Once the test
completes, the DEF pump purges the system. The
amount of DEF in the container must be checked to
see if the mass meets the specification.
The dosing rate is 0.33 g/s (0.012 oz/s) over a period
of 6 minutes. The amount of DEF collected must be
within 105 mL (3.57 fl oz) and 130 mL (4.42 fl oz).
DEF Dosing System Verification Test
This test primes the dosing system to the required
pressure for dosing. The test checks that the DEF
pump is able to build adequate pressure and ensure
that there are no leaks in the system.
UENR4469-36 459
Service
Copyright of Perkins Engine Company Limited. NOT FOR REPRINTING OR RESALE
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