Manitowoc Published 05-16-17, Control # 233-03 7-17
999 SERVICE/MAINTENANCE MANUAL POWER TRAIN
DEF Dosing Module
The DEF dosing module (8) injects a liquid mixture of urea
and deionized water (called DEF) into the exhaust stream
ahead of the inlet to the SCR module (6). Coolant lines run
through the dosing module to keep it cool and operable.
DOC Module
The primary function of the DOC module (9) is to oxidize the
remaining hydrocarbons in the exhaust to carbon dioxide. It
incorporates a NO
x
sensor, a dP sensor, and two
temperature sensors.
The DOC module does not require maintenance.
DEF Heating and Cooling System
See Figure 7-11 for coolant hose routing and flow direction.
Warm coolant from the engine is routed to the coolant
manifold (3) where it splits into two paths: one path delivers
coolant to the heat exchanger in the DEF tank (1) to keep the
DEF warm, and the other path delivers coolant to the DEF
dosing module (8) to keep it from overheating.
The coolant solenoid valve (2) adjusts coolant flow according
to the temperature of the DEF in the DEF tank. If the tank
temperature drops below 25°F (–4°C), the ECM will open the
solenoid valve, and engine coolant will flow through the heat
exchanger in the DEF tank.
To keep the DEF flowing during cold temperatures, two
heating elements are provided: one in the DEF supply
module and one in DEF line. The heating elements turn on if
the ambient air temperature sensor reads a temperature
below 25°F (–4°C).
The DEF dosing module (8) will not prime the system until
every component is completely defrosted. If ambient
conditions continue to be cold after the system has primed,
the ECM will command a maintenance heating cycle to
prevent the DEF system from refreezing. This feature will
cycle the heating on and off to the DEF lines, DEF tank, and
dosing module.
NOTE: DEF will freeze at 12°F (–11°C) and when frozen
will expand by 7%. There are no approved
additives to improve the freezing point.
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