1 ENGINE SYSTEMS 45
Exhaust Gas Recirculation (EGR) Control Valve
The EGR valve c ontrols the flow of exhaust gases into
the inlet and EGR mixer duct.
The EGR drive module controls the EGR actuator.
The EGR drive module receives the desired EGR
actuator position from the ECM across the CAN
2 d atalink to activate the valve for exhaust gas
recirculation. The EGR drive module provides
feedback to the ECM on the valve position.
The EGR drive module constantly monitors the EGR
actuator. W hen an EGR control error is detected, the
EGR drive module sends a message to the ECM and
aDTCisset.
Brake Shut-off Val ve
The brake shut-off valve controls pressure in the oil
gallery of the high-pressure oil rail. When the en gin e
brake is activated, the ECM provides power to activate
the brake shut-off v alve to allow oil from the injector
oil gallery to flow to the brake oil gallery. High oil
pressure activates the brake actuator pistons to open
the exhaust valves.
Injection Pressure Regulator (IPR)
The IPR valve controls pressure in the Injection
Control Pressure (ICP) system. The IPR valve is a
variable position v alv e controlled by th e ECM. This
regulated pressure actuates the fuel injectors. The
valve pos ition is contro lled by switch in g the ground
circuit in the ECM. The voltage source is supplied by
the ignition switc h.
Inlet Air Heater (IAH)
The IAH syst em warms the in co ming air supp ly prior to
cranking to aid cold engine starting and reduce white
smoke during w arm-up.
TheECMisprogrammedtoenergizetheIAH
elements through the IAH relays w hile monitoring
certain programmed conditions for engine coolant
temperature, engine oil temperature, and atmospheric
pressure.
Injection Drive Module (IDM)
Figure 37 Injection Drive Module (IDM)
1. Camshaft with peg
2. Camshaft Positio n (CMP) signal
3. Crankshaft position sensor timing disk
4. Crankshaft Position (CKP) sig nal
5. Electronic Control Modu le (ECM)
6. Camshaft Position Output (CMPO) signal
7. Crankshaft Position Output (CKPO) signal
8. Control ler Area Network (CAN 2) communication
9. Injection Drive Module (IDM)
10. Fuel injectors
The IDM has three functions:
• Electronic distributor for injectors
• Power source for injectors
• IDM and injector diagnostics
Electronic Distributor for Injectors
The IDM distributes current to the injectors. The IDM
controls fueling to the engine by s ending high voltage
pulses to the OPEN and CLOSE coils of the injector.
The IDM uses information from the ECM to determine
the timing and quantity of fuel for each injector.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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