Jeep Cherokee 2000 Service Manual - page 1249
FUEL INJECTION SYSTEM—2.5L DIESEL ENGINE
TABLE OF CONTENTS
page
page
DESCRIPTION AND OPERATION
FUEL INJECTION SYSTEM . . . . . . . . . . . . . . . . . 23
POWERTRAIN CONTROL MODULE (PCM) . . . . . 24
BOOST PRESSURE SENSOR . . . . . . . . . . . . . . . 25
VEHICLE THEFT ALARM . . . . . . . . . . . . . . . . . . . 25
BATTERY VOLTAGE—PCM INPUT. . . . . . . . . . . . 25
SENSOR RETURN—ECM/PCM INPUT
(ANALOG GROUND) . . . . . . . . . . . . . . . . . . . . . 26
IGNITION CIRCUIT SENSE—ECM/PCM INPUT . . 26
IGNITION CIRCUIT SENSE—PCM INPUT . . . . . . 26
POWER GROUND . . . . . . . . . . . . . . . . . . . . . . . . 26
NEEDLE MOVEMENT OR INTRUMENTED
FIRST INJECTOR—ECM INPUT . . . . . . . . . . . . 26
FUEL INJECTOR SENSOR—GROUND. . . . . . . . . 26
ENGINE COOLANT TEMPERATURE
SENSOR—ECM/PCM INPUT. . . . . . . . . . . . . . . 26
ENGINE SPEED SENSOR—ECM INPUT . . . . . . . 26
AIR CONDITIONING (A/C) CONTROLS—ECM
INPUTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
BRAKE SWITCH—ECM INPUT. . . . . . . . . . . . . . . 28
DATA LINK CONNECTOR—PCM AND ECM
INPUT AND OUTPUT . . . . . . . . . . . . . . . . . . . . 28
VEHICLE SPEED SENSOR—ECM INPUT . . . . . . 28
SPEED CONTROL—ECM INPUT . . . . . . . . . . . . . 28
ASD RELAY—ECM INPUT . . . . . . . . . . . . . . . . . . 29
FIVE VOLT POWER—ECM/PCM OUTPUT . . . . . . 29
ENGINE COOLANT GAUGE—PCM OUTPUT . . . . 29
ENGINE OIL PRESSURE GAUGE—PCM
OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
GLOW PLUG LAMP—PCM OUTPUT . . . . . . . . . . 29
SPEED CONTROL—PCM OUTPUTS . . . . . . . . . . 29
AIR CONDITIONING RELAY—ECM OUTPUT . . . . 29
TIMING SOLENOID—ECM OUTPUT . . . . . . . . . . 29
TACHOMETER—PCM OUTPUT . . . . . . . . . . . . . . 30
GLOW PLUG RELAY—ECM OUTPUT . . . . . . . . . 30
GLOW PLUGS . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
ELECTRIC VACUUM MODULATOR (EVM)—
ECM OUTPUT. . . . . . . . . . . . . . . . . . . . . . . . . . 31
DIAGNOSIS AND TESTING
DIESEL DIAGNOSTICS . . . . . . . . . . . . . . . . . . . . 31
ASD RELAY TEST . . . . . . . . . . . . . . . . . . . . . . . . 31
ENGINE SPEED SENSOR TEST . . . . . . . . . . . . . 31
ENGINE COOLANT TEMPERATURE SENSOR
TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
GLOW PLUG TEST . . . . . . . . . . . . . . . . . . . . . . . 31
GLOW PLUG RELAY TEST . . . . . . . . . . . . . . . . . 33
RELAYS—OPERATION/TESTING . . . . . . . . . . . . . 34
BOOST / PRESSURE SENSOR . . . . . . . . . . . . . . 34
VEHICLE SPEED SENSOR TEST. . . . . . . . . . . . . 35
DIAGNOSTIC TROUBLE CODES . . . . . . . . . . . . . 35
REMOVAL AND INSTALLATION
ASD RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A/C CLUTCH RELAY . . . . . . . . . . . . . . . . . . . . . . 35
ENGINE SPEED SENSOR . . . . . . . . . . . . . . . . . . 35
ENGINE COOLANT TEMPERATURE SENSOR . . . 35
GLOW PLUGS . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
GLOW PLUG RELAY . . . . . . . . . . . . . . . . . . . . . . 36
POWERTRAIN CONTROL MODULE (PCM) . . . . . 36
VEHICLE SPEED SENSOR . . . . . . . . . . . . . . . . . 37
SPECIFICATIONS
GLOW PLUG CURRENT DRAW . . . . . . . . . . . . . . 38
TORQUE CHART—2.5L DIESEL. . . . . . . . . . . . . . 38
DESCRIPTION AND OPERATION
FUEL INJECTION SYSTEM
DESCRIPTION
This section will cover components either regulated
or controlled by the ECM controller and the Power-
train Control Module (PCM). The fuel heater relay
and fuel heater are not operated by the ECM control-
ler or the PCM. These components are controlled by
the ignition (key) switch. All other fuel system elec-
trical components necessary to operate the engine
are controlled or regulated by the ECM controller,
which interfaces with the PCM. Refer to the follow-
ing description for more information.
Certain fuel system component failures may cause
a no start, or prevent the engine from running. It is
important to know that the ECM has a feature
where, if possible, it will ignore the failed sensor, set
a code related to the sensor, and operate the engine
in a “Limp Home” mode. When the ECM is operating
in a “Limp Home” mode, the Check Engine Lamp on
the instrument panel may be constantly illuminated,
and the engine will most likely have a noticeable loss
of performance. An example of this would be an
Accelerator Pedal Position Sensor failure, and in that
situation, the engine would run at a constant 1100
RPM, regardless of the actual position of the pedal.
This is the most extreme of the three “Limp Home”
modes.
When the Check Engine Lamp is illuminated con-
stantly with the key on and the engine running, it
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