SECTION 01: ENGINE
PA1553
7
2.13 OIL TEMPERATURE SENSOR
The Oil Temperature Sensor (OTS) is installed
behind the engine oil filters manifold (Fig. 1).
The OTS sends an electrical signal to the ECM
indicating engine oil temperature. The ECM
uses this information to modify engine speed for
better cold weather starts and faster warm-ups.
Oil temperatures exceeding engine
specifications for two seconds or more will
illuminate the Check Engine Light.
The OTS is non-serviceable and must be
replaced as a unit. No adjustment is required.
3. ENGINE-RELATED COMPONENTS
Engine-related components include:
o Coolant Level System (CLS)
o Electronic Foot Pedal Assembly (EFPA) and
Throttle Position Sensor
o Cruise Control Switch (CCS)
o Diagnostic System Accessories (DSA)
3.1 COOLANT LEVEL SYSTEM (CLS)
The coolant level system consists of a
conductivity probe mounted in the surge tank
and an electronic interface module located
inside the rear junction box. Coolant level is
determined by the change in impedance of the
probe and its brass mount when immersed in
coolant. The electronic device in the module
conditions the signal to levels compatible with
DDEC. A low coolant level will trigger the engine
warning functions.
The probe and electronic interface module are
non-serviceable items and should be replaced
as units, if found defective. No adjustment is
required.
3.2 ELECTRONIC FOOT PEDAL ASSEMBLY
(EFPA) & THROTTLE POSITION SENSOR
The Electronic Foot Pedal Assembly (EFPA)
connects the accelerator pedal to a Throttle
Position Sensor (TPS). The (TPS) is a device,
which sends an electrical signal to the Electronic
Control Module (ECM). The TPS signal varies in
voltage depending on how far the pedal is
depressed. The system is installed in the space
normally occupied by a mechanical foot pedal.
The (EFPA) has maximum and minimum stops
that are built into the unit during manufacturing
(Fig. 11). The (TPS) converts the operator's foot
pedal input into a signal for the ECM. The
(EFPA) is shown in Figure 11.
When installed by the equipment manufacturer,
the TPS should not require adjustment. If the
TPS is suspected of being misadjusted, confirm
that the sensor is installed in accordance with
the manufacturer's specifications. It is
recommended that the idle count be at 50 or
higher with a full throttle count of up to 200.
The TPS is self-calibrating and therefore has no
optimum closed throttle or wide open throttle
count value. If the counts are within the 50 to
200 range, the sensor is properly set.
FIGURE 11: ELECTRONIC FOOT PEDAL ASSEMBLY
03035
Monitor the (TPS) at the controls as you move it
through its full stroke. Be sure there is no
misalignment or obstruction preventing the
smooth movement of the TPS through the full
stroke. Using a diagnostic data reader, check
that the idle and full throttle position counts do
not fall within the error zones. The error zones
occur when the idle position is less than 14
counts, or when the full throttle position is more
than 233 counts. Should these conditions occur,
the ECM will signal diagnostic codes of 21-12
for idle error and 21-23 for wide-open throttle
error.
3.3 CRUISE CONTROL SWITCHES (CCS)
The four cruise control switches are located in
the driver's area on the L.H. side control panel.
1.
Cruise: This is the main switch that actuates
the ECM memory in order to use the speed-
regulating mode.
2.
Set: This switch is used to set the cruise
control speed or to decrease the set speed
by 2 MPH at each application.
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