Jeep 200 Cherokee, Service Manual

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Speed Control Lamp
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ASD Relay
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5 Volts Supply
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Fuel Quantity Actuator
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Fuel Timing Solenoid
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Fuel Shutdown Solenoid
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Glow Plug Lamp
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Check Engine Lamp (“On/Off” signal)
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Electric Vacuum Modulator (EVM)
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Glow Plug Relay
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Tachometer
The PCM sends and recieves signals to and from
the ECM controller. PCM inputs are:
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Power Gound
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5 Volts Supply
•
Vehicle Speed Sensor
•
Water-In-Fuel Sensor
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Coolant Temperature Sensor
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Low Coolant Sensor
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Sensor Return
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Fuel Level Sensor
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Oil Pressure Sensor
•
Tachometer Signal
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Glow Plug Lamp
•
Check Engine Lamp (“On/Off” signal)
•
Brake On/Off Switch
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Battery Voltage
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ASD Relay
PCM Outputs:
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A/C On Signal
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Vehicle Theft Alarm “Ok to Run” signal
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Body Control Module CCD Bus (+)
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Body Control Module CCD Bus (–)
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Scan Tool Data Link Recieve
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Scan Tool Data Link Transmit
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Low Coolant Lamp
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Generator Control
BOOST PRESSURE SENSOR
DESCRIPTION
The Boost Pressure Sensor is mounted to the top of
the intake manifold (Fig. 3). It is a sensor that mea-
sures both manifold vacuum and turbo boost, and it
also contains an integrated intake air temperature
sensor. The Boost Pressure Sensor takes the place of
the Mass Air Flow (MAF). In the Intake Air Temper-
ature Sensor component, there is a ceramic element
that changes its resistance based on temperature.
The ceramic element is part of an electronic circuit
connected to the PCM, and has a voltage applied to
it. The ceramic element is exposed to the air inside
the intake. This air has a cooling effect on the
ceramic element, and its resistance changes. This
causes the voltage flowing through the intake air
temperature circuit to vary. The voltage signal pro-
duced by the Intake Air Temperature Sensor changes
inversely to the temperature, and is measured by the
PCM. As a general rule, when the temperature of the
air in the intake is high, the voltage signal produced
by the Intake Air Temperature Sensor is low. The
component of the Boost Pressure Sensor that mea-
sures manifold vacuum and turbo boost produces a
voltage signal that is proportional to the pressure in
the intake manifold. When the intake manifold pres-
sure is low, the voltage is low, and when the pressure
is high, the voltage is high. The PCM uses the volt-
age signals from the Boost Pressure Sensor, and the
Intake Air Temperature Sensor to determine the
amount of air flowing through the intake manifold.
VEHICLE THEFT ALARM
DESCRIPTION
The PCM can learn if the vehicle has a Vehicle
Theft Alarm (VTA) system. Once it detects the vehi-
cle having VTA, the controller can ONLY BE
USED ON VEHICLES WITH VTA.
If the PCM is put it on a vehicle without VTA the
Glow Plug Lamp will start to blink and the vehicle
will not start.
The PCM cannot be flashed to remove the VTA.
BATTERY VOLTAGE—PCM INPUT
DESCRIPTION
The battery voltage input provides power to the
PCM. It also informs the PCM what voltage level is
being supplied by the generator once the vehicle is
running.
Fig. 3 Boost Pressure Sensor Location
1 – BOOST PRESSURE SENSOR HARNESS CONNECTOR
2 – BOOST PRESSURE SENSOR
XJ
FUEL SYSTEM—2.5L DIESEL ENGINE 14 - 25
DESCRIPTION AND OPERATION (Continued)