Navistar International DT 466 Diagnostic/Troubleshooting Manual page 56

52
Figure 44 Switch
1. Accelerator pedal
2. Idle Validation Switch (IVS)
3. Voltage source with current limiting resistor
4. Microprocessor
5. ECM
6. Ground
Switches
• DDS
• ECL
• IVS
• WIF
Switch sensors indicate position, level, or status.
They operate open or closed, allowing or preventing
the flow of current. A switch sensor can be a voltage
input switch or a grounding switch. A voltage input
switch supplies the ECM with a voltage when it is
closed. A grounding switch grounds the circuit when
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
1 ENGINE SYSTEMS
closed, causing a zero voltage signal. Grounding
switches are usually installed in series with a current
limiting resistor.
Driveline Disengagement Switch (DDS)
The DDS determines if a vehicle is in gear.
manual transmissions, the clutch switch serves as
the DDS. For automatic transmissions, the neutral
indicator switch or datalink communication functions
as the DDS.
Engine Coolant Level (ECL)
ECL is part of the Engine Warning Protection System
(EWPS). The ECL switch is used in plastic deaeration
tanks. When a magnetic switch is open, the tank is
full.
If engine coolant is low, the red ENGINE lamp on the
instrument panel is illuminated.
Idle Validation Switch (IVS)
The IVS is a redundant switch that provides the ECM
with a signal that verifies when the APS is in the idle
position.
Water In Fuel (WIF)
A Water In Fuel (WIF) sensor in the element cavity
of the fuel filter housing detects water. When enough
water accumulates in the element cavity, the WIF
sensor signal changes to the Electronic Control
Module (ECM). The ECM sends a message to
illuminate the amber water and fuel lamp, alerting the
operator. The WIF is installed in the base of the fuel
filter housing.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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