exj 25, JEEP Manuals, Electronic Service Manual (jeep cherokee xj do 2000)
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XJ
EMISSION CONTROL SYSTEMS
25 - 1
EMISSION CONTROL SYSTEMS
TABLE OF CONTENTS
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page
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3
ON-BOARD DIAGNOSTICS
TABLE OF CONTENTS
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page
DESCRIPTION AND OPERATION
DIAGNOSTIC TROUBLE CODE
DESCRIPTION AND OPERATION
diagnostic trouble code criteria requires the PCM to
monitor the circuit only when the engine operates
between 750 and 2000 RPM. Suppose the sensor’s
output circuit shorts to ground when engine operates
above 2400 RPM (resulting in 0 volt input to the
PCM). Because the condition happens at an engine
speed above the maximum threshold (2000 rpm), the
PCM will not store a DTC.
There are several operating conditions for which
the PCM monitors and sets DTC’s. Refer to Moni-
tored Systems, Components, and Non-Monitored Cir-
cuits in this section.
Technicians must retrieve stored DTC’s by connect-
ing the DRB scan tool (or an equivalent scan tool) to
the 16–way data link connector (Fig. 1).
EMISSION SYSTEM
OPERATION
The Powertrain Control Module (PCM) monitors
many different circuits in the fuel injection, ignition,
emission and engine systems. If the PCM senses a
problem with a monitored circuit often enough to
indicate an actual problem, it stores a Diagnostic
Trouble Code (DTC) in the PCM’s memory. If the
code applies to a non-emissions related component or
system, and the problem is repaired or ceases to
exist, the PCM cancels the code after 40 warm-up
cycles. Diagnostic trouble codes that affect vehicle
emissions illuminate the Malfunction Indicator Lamp
(MIL). The MIL is displayed as an engine icon on the
instrument
NOTE: Various diagnostic procedures may actually
cause a diagnostic monitor to set a DTC. For
instance, pulling a spark plug wire to perform a
spark test may set the misfire code. When a repair
is completed and verified, connect the DRB scan
tool to the 16–way data link connector to erase all
DTC’s and extinguish the MIL.
panel.
Refer
to
Malfunction
Indicator
Lamp (MIL) in this section.
Certain criteria must be met before the PCM
stores a DTC in memory. The criteria may be a spe-
cific
range
of
engine
RPM,
engine
temperature,
and/or input voltage to the PCM.
The PCM might not store a DTC for a monitored
circuit even though a malfunction has occurred. This
may happen because one of the DTC criteria for the
circuit has not been met.
For example
, assume the
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EMISSION CONTROL SYSTEMS
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DESCRIPTION AND OPERATION (Continued)
10 % of the load of the operating condition at which
the malfunction was first detected.
STATE DISPLAY TEST MODE
OPERATION
The switch inputs to the Powertrain Control Mod-
ule (PCM) have two recognized states; HIGH and
LOW. For this reason, the PCM cannot recognize the
difference between a selected switch position versus
an open circuit, a short circuit, or a defective switch.
If the State Display screen shows the change from
HIGH to LOW or LOW to HIGH, assume the entire
switch circuit to the PCM functions properly. Connect
the DRB scan tool to the data link connector and
access the state display screen. Then access either
State Display Inputs and Outputs or State Display
Sensors.
CIRCUIT ACTUATION TEST MODE
Fig. 1 Data Link (Diagnostic) Connector Location
1 – 16–WAY DATA LINK CONNECTOR
OPERATION
The Circuit Actuation Test Mode checks for proper
operation of output circuits or devices the Powertrain
Control Module (PCM) may not internally recognize.
The PCM attempts to activate these outputs and
allow an observer to verify proper operation. Most of
the tests provide an audible or visual indication of
device operation (click of relay contacts, fuel spray,
etc.). Except for intermittent conditions, if a device
functions properly during testing, assume the device,
its associated wiring, and driver circuit work cor-
rectly. Connect the DRB scan tool to the data link
connector and access the Actuators screen.
MALFUNCTION INDICATOR LAMP (MIL)
DESCRIPTION
The Malfunction Indicator Lamp (MIL) is located
on the instrument panel. It is displayed as an engine
icon (graphic).
OPERATION
As a functional test, the MIL illuminates at key-on
before engine cranking. Whenever the Powertrain
Control Module (PCM) sets a Diagnostic Trouble
Code (DTC) that affects vehicle emissions, it illumi-
nates the MIL. If a problem is detected, the PCM
sends a message to the instrument cluster to illumi-
nate the lamp. The PCM illuminates the MIL only
for DTC’s that affect vehicle emissions. There are
some monitors that may take two consecutive trips,
with a detected fault, before the MIL is illuminated.
The MIL stays on continuously when the PCM has
entered a Limp-In mode or identified a failed emis-
sion component. Refer to the Diagnostic Trouble Code
charts in this group for emission related codes.
Also, the MIL either flashes or illuminates contin-
uously when the PCM detects active engine misfire.
Refer to Misfire Monitoring in this section.
Additionally, the PCM may reset (turn off) the MIL
when one of the following occur:
²
DIAGNOSTIC TROUBLE CODES
OPERATION
A Diagnostic Trouble Code (DTC) indicates that the
Powertrain Control Module (PCM) has recognized an
abnormal condition in the system.
DTC’s are the results of a system or circuit
failure, but do not directly identify the failed
component or components.
Technicians must retrieve stored DTC’s by connect-
ing the DRB III scan tool (or an equivalent scan tool)
to the 16–way data link connector. This connector is
located on the lower edge of the instrument panel
near the steering column.
PCM does not detect the malfunction for 3 con-
secutive trips (except misfire and Fuel system Moni-
tors).
²
OBTAINING DTC’s
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK WHEELS BEFORE PERFORMING ANY TEST
ON AN OPERATING ENGINE.
PCM does not detect a malfunction while per-
forming three successive engine misfire or fuel sys-
tem tests. The PCM performs these tests while the
engine is operating within
6
375 RPM of and within
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EMISSION CONTROL SYSTEMS
25 - 3
DESCRIPTION AND OPERATION (Continued)
(1) Connect the DRB scan tool to data link (diag-
nostic) connector.
(2) Turn the ignition switch on, access Read Fault
Screen. Record all the DTC’s shown on the DRB scan
tool.
(3) To erase DTC’s, use the Erase Trouble Code
data screen on the DRB scan tool.
NOTE: For a list of DTC’s, refer to the following
charts.
DIAGNOSTIC TROUBLE CODE DESCRIPTIONS
(M)
Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was
recorded (depending if required by CARB and/or EPA). MIL is displayed as an engine icon on
instrument panel.
(G)
Generator lamp illuminated
Generic Scan
Tool P-Code
DRB Scan Tool Display
Brief Description of DTC
P0030 (M)
1/1 O2 Sensor Heater Relay Circuit
Problem detected in oxygen sensor heater relay circuit.
P0036 (M)
1/2 O2 Sensor Heater Relay Circuit
Problem detected in oxygen sensor heater relay circuit.
P0106
Barometric Pressure Out of Range
MAP sensor input voltage out of an acceptable range
detected during reading of barometric pressure at key-on.
P0107 (M)
Map Sensor Voltage Too Low
MAP sensor input below minimum acceptable voltage.
P0108 (M)
Map Sensor Voltage Too High
MAP sensor input above maximum acceptable voltage.
P0112 (M)
Intake Air Temp Sensor Voltage Low
Intake air (charge) temperature sensor input below the
minimum acceptable voltage.
P0113 (M)
Intake Air Temp Sensor Voltage High
Intake air (charge) temperature sensor input above the
maximum acceptable voltage.
P0116
A rationatilty error has been detected in the coolant temp
sensor.
P0117 (M)
ECT Sensor Voltage Too Low
Engine coolant temperature sensor input below the
minimum acceptable voltage.
P0118 (M)
ECT Sensor Voltage Too High
Engine coolant temperature sensor input above the
maximum acceptable voltage.
P0121 (M)
TPS Voltage Does Not Agree With
MAP
TPS signal does not correlate to MAP sensor signal.
P0121 (M)
Accelerator Position Sensor (APPS)
Signal Voltage Too Low
APPS voltage input below the minimum acceptable
voltage.
P0122 (M)
Throttle Position Sensor Voltage Low
Throttle position sensor input below the acceptable
voltage range.
P0122 (M)
Accelerator Position Sensor (APPS)
Signal Voltage Too Low
APPS voltage input below the minimum acceptable
voltage.
P0123 (M)
Throttle Position Sensor Voltage
High
Throttle position sensor input above the maximum
acceptable voltage.
P0123 (M)
Accelerator Position Sensor (APPS)
Signal Voltage Too High
APPS voltage input above the maximum acceptable
voltage.
P0125 (M)
Closed Loop Temp Not Reached
Time to enter Closed Loop Operation (Fuel Control) is
excessive.
P0125 (M)
Engine is Cold Too Long
Engine does not reach operating temperature.
P0130 (M)
1/1 O2 Sensor Heater Circuit
Malfunction
Oxygen sensor heater element malfunction.
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EMISSION CONTROL SYSTEMS
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DESCRIPTION AND OPERATION (Continued)
(M)
Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was
recorded (depending if required by CARB and/or EPA). MIL is displayed as an engine icon on
instrument panel.
P0131 (M)
1/1 O2 Sensor Shorted To Ground
Oxygen sensor input voltage maintained below normal
operating range.
P0132 (M)
1/1 O2 Sensor Shorted To Voltage
Oxygen sensor input voltage maintained above normal
operating range.
P0133 (M)
1/1 O2 Sensor Slow Response
Oxygen sensor response slower than minimum required
switching frequency.
P0134 (M)
1/1 O2 Sensor Stays at Center
Neither rich or lean condition is detected from the oxygen
sensor input.
P0135 (M)
1/1 O2 Sensor Heater Failure
Oxygen sensor heater element malfunction.
P0136 (M)
1/2 O2 Sensor Heater Circuit
Malfunction
Oxygen sensor heater element malfunction.
P0137 (M)
1/2 O2 Sensor Shorted To Ground
Oxygen sensor input voltage maintained below normal
operating range.
P0138 (M)
1/2 O2 Sensor Shorted To Voltage
Oxygen sensor input voltage maintained above normal
operating range.
P0139 (M)
1/2 O2 Sensor Slow Response
Oxygen sensor response not as expected.
P0140 (M)
1/2 O2 Sensor Stays at Center
Neither rich or lean condition is detected from the oxygen
sensor.
P0141 (M)
1/2 O2 Sensor Heater Failure
Oxygen sensor heater element malfunction.
P0143 (M)
1/3 O2 Sensor Shorted To Ground
Oxygen sensor input voltage maintained below normal
operating range.
P0144 (M)
1/3 O2 Sensor Shorted To Voltage
Oxygen sensor input voltage maintained above normal
operating range.
P0145 (M)
1/3 O2 Sensor Slow Response
Oxygen sensor response slower than minimum required
switching frequency.
P0146 (M)
1/3 O2 Sensor Stays at Center
Neither rich or lean condition is detected from the oxygen
sensor.
P0147 (M)
1/3 O2 Sensor Heater Failure
Oxygen sensor heater element malfunction.
P0151 (M)
2/1 O2 Sensor Shorted To Ground
Oxygen sensor input voltage maintained below normal
operating range.
P0152 (M)
2/1 O2 Sensor Shorted To Voltage
Oxygen sensor input voltage sustained above normal
operating range.
P0153 (M)
2/1 O2 Sensor Slow Response
Oxygen sensor response slower than minimum required
switching frequency.
P0154 (M)
2/1 O2 Sensor Stays at Center
Neither rich or lean condition is detected from the oxygen
sensor.
P0155 (M)
2/1 O2 Sensor Heater Failure
Oxygen sensor heater element malfunction.
P0157 (M)
2/2 O2 Sensor Shorted To Ground
Oxygen sensor input voltage maintained below normal
operating range.
P0158 (M)
2/2 O2 Sensor Shorted To Voltage
Oxygen sensor input voltage maintained above normal
operating range.
P0159
2/2 O2 Sensor Slow Response
Oxygen sensor response slower than minimum required
switching frequency.
P0160 (M)
2/2 O2 Sensor Stays at Center
Neither rich or lean condition is detected from the oxygen
sensor.
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EMISSION CONTROL SYSTEMS
25 - 5
DESCRIPTION AND OPERATION (Continued)
(M)
Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was
recorded (depending if required by CARB and/or EPA). MIL is displayed as an engine icon on
instrument panel.
P0161 (M)
2/2 O2 Sensor Heater Failure
Oxygen sensor heater element malfunction.
P0168
Decreased Engine Performance Due
To High Injection Pump Fuel Temp
Fuel temperature is above the engine protection limit.
Engine power will be derated.
P0171 (M)
1/1 Fuel System Lean
A lean air/fuel mixture has been indicated by an
abnormally rich correction factor.
P0172 (M)
1/1 Fuel System Rich
A rich air/fuel mixture has been indicated by an
abnormally lean correction factor.
P0174 (M)
2/1 Fuel System Lean
A lean air/fuel mixture has been indicated by an
abnormally rich correction factor.
P0175 (M)
2/1 Fuel System Rich
A rich air/fuel mixture has been indicated by an
abnormally lean correction factor.
P0176
Loss of Flex Fuel Calibration Signal
No calibration voltage present from flex fuel sensor.
P0177
Water In Fuel
Excess water found in fuel by water-in-fuel sensor.
P0178
Flex Fuel Sensor Volts Too Low
Flex fuel sensor input below minimum acceptable voltage.
P0178
Water In Fuel Sensor Voltage Too
Low
Loss of water-in-fuel circuit or sensor.
P0179
Flex Fuel Sensor Volts Too High
Flex fuel sensor input above maximum acceptable
voltage.
P0181
Fuel Injection Pump Failure
Low power, engine derated, or engine stops.
P0182 (M)
CNG Temp Sensor Voltage Too Low
Compressed natural gas temperature sensor voltage
below acceptable voltage.
P0183 (M)
CNG Temp Sensor Voltage Too High
Compressed natural gas temperature sensor voltage
above acceptable voltage.
P0201 (M)
Injector #1 Control Circuit
An open or shorted condition detected in control circuit for
injector #1 or the INJ 1 injector bank.
P0202 (M)
Injector #2 Control Circuit
An open or shorted condition detected in control circuit for
injector #2 or the INJ 2 injector bank.
P0203 (M)
Injector #3 Control Circuit
An open or shorted condition detected in control circuit for
injector #3 or the INJ 3 injector bank.
P0204 (M)
Injector #4 Control Circuit
Injector #4 or INJ 4 injector bank output driver stage does
not respond properly to the control signal.
P0205 (M)
Injector #5 Control Circuit
Injector #5 output driver stage does not respond properly
to the control signal.
P0206 (M)
Injector #6 Control Circuit
Injector #6 output driver stage does not respond properly
to the control signal.
P0207 (M)
Injector #7 Control Circuit
Injector #7 output driver stage does not respond properly
to the control signal.
P0208 (M)
Injector #8 Control Circuit
Injector #8 output driver stage does not respond properly
to the control signal.
P0209 (M)
Injector #9 Control Circuit
Injector #9 output driver stage does not respond properly
to the control signal.
P0210 (M)
Injector #10 Control Circuit
Injector #10 output driver stage does not respond properly
to the control signal.
P0215
Fuel Injection Pump Control Circuit
Failure in fuel pump relay control circuit.
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