Page 420
REPAIR INSTRUCTIONS, PART 2
MASS Flow System Replacement
Instructions
The EGR MASS Flow sensors are an integral
part of the upper EGR gas tube and cannot be
removed. The sensors are calibrated specifically
to the upper EGR tube and the EGR MASS Flow
System module. If replacement is required, the
entire tube assembly with its integral sensors
must be replaced along with the MASS Flow
System module attached to the back of the EECU
cooling plate.
Effective with engine production beginning
5/15/03, changes were made to the MASS Flow
System (MFS) and the Engine Electronic Control
Unit (EECU) cooling plate on which the MFS
electronic module is mounted. These MFS
changes caused the sensor wire harness to be
shortened from 39 inches (99.06 cm) to 30 inches
(76.2 cm). The module cooling plate was also
revised to mount the MASS flow module toward
the rear of the cooling plate with the harness
connector also facing the rear. Depending upon
the availability of parts through the MACK Parts
System, it is acceptable to use either wire length
MASS flow system in place of the other. MASS
flow system parts for non-brake and
brake-equipped engines, however, are not
interchangeable.
The following description covers the differences
between the MASS flow system used on engines
manufactured prior to 5/15/03 and the system
after this date:
앫 For engines manufactured prior to 5/15/03,
the EGR tube and sensor assemblies
contain harness wires that are
approximately 39 inches (99.06 cm) long.
These wire harnesses route from the
sensors, around the front of the engine to
the MFS electronic module which is
mounted on the EECU cooling plate. With
this longer harness, the MFS module
harness connectors will face the front of the
engine.
앫 For engines manufactured after 5/15/03, the
EGR tube and sensor assemblies contain
harness wires that are approximately
30 inches (76.2 cm) long. These wire
harnesses are routed over the top of the
front cylinder head cover to the MASS flow
system electronic module. For this
configuration, the module is mounted on the
EECU cooling plate with the harness facing
the rear of the chassis.
MASS FLOW SYSTEM INSTALLATION
EGR Tube Installation Instructions
To properly install the EGR tube assembly, the
clamps must be fully seated by tapping each
clamp with a rubber mallet and torquing three
times as described in “EGR Gas Tube(s)
Removal and Installation” on page 402.
MASS Flow System Module Installation
Instructions
The MASS flow system module is mounted on
the back of the engine electronic control unit
(EECU) cooling plate. To replace the module, it is
necessary to disconnect the EECU and mass
flow system module connectors, then to remove
the EECU, cooling plate and MASS flow system
module as an assembly. Once the cooling plate is
removed, the four screws retaining the module to
the plate can be accessed and removed.
Installation of the MFS module can either be
facing toward the front or the rear of the chassis
depending on configuration of the cooling plate.
1. Reinstall the four module retaining screws
and torque to specifications.
2. Route the sensor wire harness either over
top of the front valve cover or around the
front of the engine depending on harness
length and configuration.
3. Clamp and tie the harnesses as necessary
to prevent the harness from rubbing against
any engine components.
5-111.bk Page 420 Monday, July 10, 2006 2:26 PM
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