Dodge ZB 2005, Service Manual

Page: 1090 / 1873

EMISSIONS CONTROL
TABLE OF CONTENTS
page page
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - MONITORED COMPONENT . 1
DESCRIPTION - VEHICLE EMISSION
CONTROL INFORMATION LABEL . . . . . . . . . . 4
DESCRIPTION - TRIP DEFINITION . . . . . . . . . 5
OPERATION - NON-MONITORED CIRCUITS . . 5
DESCRIPTION - MONITORED SYSTEMS . . . . 6
DESCRIPTION - HIGH AND LOW LIMITS . . . . 8
OPERATION
OPERATION - SYSTEM . . . . . . . . . . . . . . . . . . 8
DRB III
T
STATE DISPLAY TEST MODE . . . . . . 9
EVAPORATIVE EMISSIONS . . . . . . . . . . . . . . . . 10
ON-BOARD DIAGNOSTICS . . . . . . . . . . . . . . . . 18
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - MONITORED COMPONENT
There are several components that will affect vehi-
cle emissions if they malfunction If one of these com-
ponents
malfunctions the Malfunction Indicator
Lamp (Check Engine) will illuminate.
Some of the component monitors are checking for
proper operation of the part. Previously, a component
like the Throttle Position sensor (TPS) was checked
by the PCM for an open or shorted circuit. If one of
these conditions occurred, a DTC was set. Now there
is a check to ensure that the component is working.
Electrically operated components now have input
(rationality) and output (functionality) checks.
Any component that has an associated limp in will
set a fault after 1 trip with the malfunction present.
Refer to the Diagnostic Trouble Codes Description
Charts and the appropriate Powertrain Diagnostic
Procedure Manual for diagnostic procedures.
The following is a list of the monitored compo-
nents:
•
Comprehensive Components
•
Oxygen Sensor Monitor
•
Oxygen Sensor Heater Monitor
•
Catalyst Monitor
COMPREHENSIVE COMPONENTS
Along with the major monitors, OBD II requires
that the diagnostic system monitor any component
that could affect emissions levels. In many cases,
these components were being tested under OBD I.
The OBD I requirements focused mainly on testing
emissions-related components for electrical opens and
shorts.
However, OBD II also requires that inputs from
powertrain components to the PCM be tested for
rationality, and that outputs to powertrain compo-
nents from the PCM be tested for functionality.
Methods for monitoring the various Comprehensive
Component monitoring include:
(1) Circuit Continuity
•
Open
•
Shorted high
•
Shorted to ground
(2) Rationality or Proper Functioning
•
Inputs tested for rationality
•
Outputs tested for functionality
NOTE: Comprehensive component monitors are
continuous. Therefore, enabling conditions do not
apply.
Input Rationality—While input signals to the
PCM are constantly being monitored for electrical
opens and shorts, they are also tested for rationality.
This means that the input signal is compared against
other inputs and information to see if it makes sense
under the current conditions.
PCM sensor inputs that are checked for rationality
include:
•
Manifold Absolute Pressure (MAP) Sensor
•
Oxygen Sensor (O2S)
•
Engine Coolant Temperature (ECT) Sensor
•
Camshaft Position (CMP) Sensor
•
Vehicle Speed Sensor
•
Crankshaft Position (CKP) Sensor
•
Intake/inlet Air Temperature (IAT) Sensor
•
Throttle Position (TPS) Sensor
•
Ambient/Battery Temperature Sensors
•
Oxygen Sensor Heater
•
Leak Detection Pump Switch
Output Functionality—PCM outputs are tested
for functionality in addition to testing for opens and
shorts. When the PCM provides a voltage to an out-
put component, it can verify that the command was
carried out by monitoring specific input signals for
expected changes. For example, when the PCM com-
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EMISSIONS CONTROL 25 - 1