7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS 335
• Exhaust Ga s Re circu lat ion (EGR) actuator
• ENGIN E lamp (am ber)
Function
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.
The ECM removes the power from the brake shut-off
valve to deactivate the engine brake. Residual brake
gallery pressure in itially bleed s from th e actuator bore.
When brake gallery pressure re aches 1000 psi, the
brake pressure relief valve opens, and oil drains back
to sump.
The brake shut-off valve consists of a solenoid and
valve assembly and is located in the center of the
high-pressure oil rail.
The E CM mo nitors the following criteria to make sure
certain conditions are m et.
• ABS (inactive)
• RPM (greater than 1200 )
• APS (less than 5%)
• EOT (greater than 60 °C [140 °F])
• Idle validation
• Operato r input switches (On/Off) (power selection
– Low, Medium, High)
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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