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7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
Remote Preset
When in the preset mode, the set switch will cause
the engine to run at the programmed set speed. The
RESUME/ACCEL switch will allow the engine to run
at the programmed resume speed.
With the remote preset enabled, the speed is adjusted
as with In-Cab preset. See In-Cab preset for more
details.
Turning the ON/OFF switch OFF, depressing the
brake pedal, clutch pedal, placing the automatic
transmission in gear, or a signal from the VSS will
deactivate the PTO speed control.
programmed option of PTO Operation Disable will
prevent the clutch and brake signals from interrupting
the PTO speed control, as well as cause the
Accelerator Position Sensor (APS) to be inoperative.
PTO speed control will not be functional if the VSS
signal is in fault.
Remote Variable
Enabling the remote variable signal allows for the
engine speed to be adjusted to the desired level.
Pressing the RESUME / ACCEL switch will cause the
engine speed to increase, pressing the SET/CRUISE
switch will cause the engine speed to decrease.
With remote variable enabled the speed is adjusted
as with In-Cab Variable.
Opening the switch to Pin X3–20, pressing the
ON/OFF switch to OFF, depressing the brake or
clutch pedal or placing the automatic transmission
in gear, or a signal from the VSS will deactivate the
PTO speed control. However the programmed option
of PTO Operation Disable will prevent the clutch
and brake signals from interrupting the PTO speed
control, as well as cause the APS to be inoperative.
PTO speed control will not be functional if the VSS
signal is in fault.
PTO Speed Ramp Rate
The rate at which the speed of the engine will change
will depend on load conditions and on a programmed
value called PTO speed ramp rate. A higher value will
cause the engine to change speed more quickly.
Tools
•
EST with INTUNE and MasterDiagnostics®
software
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
•
EZ-Tech® interface cable
•
Electrical System Troubleshooting Guide (truck
manual)
•
Electrical Circuit Diagrams (truck manual)
Fault Detection / Management
The ECM does not monitor the SCCS system for
faults.
(DTCs) for this system.
Diagnostics
However, the
If the engine does not respond to the cruise control
switches, use INTUNE to monitor cruise switch input
to the ESC. If the switch state does not change
when the cruise controls are pressed, diagnose the
cruise switch circuits using the Electrical System
Troubleshooting Guide.
the cruise switch input, use MasterDiagnostics®
to view the cruise switch state. If the switch state
does not change as the switch is pressed, verify
communication exists between the ECM and the ESC
(does the ECM respond to other ESC inputs). If the
switch state does change, verify that other conditions
do not exist that would stop or delay the reaction to
the input. Examples include:
•
rpm below minimum
•
rpm above maximum
•
Road speed below minimum / Road speed above
maximum
•
Brake pedal depressed
•
Clutch / driveline disengaged
The EST can be used to monitor the status of the PTO
controls. Comparing the data list reading to actual
operation will indicate if the controls are operating
correctly. Using the menu option of programmable
parameters the programming can be verified to
be sure the ECM is programmed correctly for the
application. Also the data list can be used to monitor
the parameters that cause interruption of PTO speed
control.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
There are no Diagnostic Trouble Codes
If the ESC is receiving
521
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