Dodge RAM TRUCK 1500 1995 Service Manual page 1701

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EMISSION CONTROL SYSTEMS 25 - 3
TYPICAL VEHICLE EMISSION CONTROL INFORMATION LABEL
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Si
IMPORTANT VEHICLE INFORMATION
THIS W H I C H CONFORMS TO U.S. EPA REGULATIONS APPLICABLE
TO XXXX MODEL YEAR NEW OGHT-DUTY TRUCKS WITH A C U »
WEIGHT GREATER THAN XXXX POUNDS AT A H ALTITUDES.
• B A S I C
KSWTtON
T I M I N G A N D I D L E F U E L / A I R M I X T U R E
HAVE
KIN
P R E S E T A T THE F A C T O R Y . S E E T H E S E R V I C E M A N U A L F O R P R O P E R
H O t t D O R E S A N D O T H E R A D D I T I O N A L I N F O R M A T I O N .
o A D J U S T M E N T S M A D E B Y O T H E R T H A N A f W O V E D SBtViCi
M A N U A L P R O C E D U R E S M A Y V I O t A T E F E D E R A L A N D S T A T E L A W S .
C A U T I O N : A P P L Y P A I W N G
MAKE
W H E N S E R V I C I N G V E H I C L E .
X X LITER
PCR5.9T5FEY4
PTAPG
SPARK PLUGS
OXXX in. GAP
RC12YC
N O ADJUSTMENTS NEEDED
T E E C O N N E C r C *
W ORIFICE
EVAP
CANISTER
R O L L O V E R V A L V E
W/ORIFICE
TO CLIMATE CONTROL
V E H I C L E S P E E D
CONTROL -
4X4 A X L E
(WHEN EQUIPPED!
I N T A K E
MANIFOLD „
ORIFICE
CHECK VALVE
W/ORIFICE
FUEL
PRESSURE
REGULATOR
to
CRANKCASE
B R E A T H E R
TO BRAKE
' BOOSTER
APPUCAIIITOXXXX
G A L L O N
FUEL TANK ONLY
J9425-7
The VECI label illustration is used as an ex­
ample only. If there are any differences between
this illustration and the actual VECI label(s), those
shown on vehicle label(s) should be used.
VACUUM HOSE ROUTING SCHEMATICS
The following vacuum hose routing schemat­
ics are used as examples only. If there are any
differences between these schematics and the Vehicle
Emission Control Information (VECI) label schemat­
ics, those shown on the VECI label should be used.
ON-BOARD DIAGNOSTICS
F O R CERTAIN EMISSION SYSTEM
COMPONENTS
The powertrain control module (PCM) performs an
On-Board Diagnostic (OBD) check for certain emis­
sion system components on all vehicles. This is done
by setting a diagnostic trouble code (DTC).
A DTC can be obtained in two different ways. One
of the ways is by connecting the DRB scan tool to the
data link connector. This connector is located in the
engine compartment (Fig. 5). Refer to the appropriate
Powertrain Diagnostic Procedures service manual for
operation of the DRB scan tool. The other way is to
cycle the ignition key and observe the malfunction in­
dicator lamp (MIL). The MIL lamp is displayed on
the instrument panel as the CHECK ENGINE lamp
(Fig. 6). This lamp will flash a numeric code. If a nu­
meric code number 32 is observed, a problem has
been found in the EGR system. If a numeric code
number 31 is observed, a problem has been found in
the EVAP system.
EGR System Check: The OBD check will activate
only during selected engine/driving conditions. When
the conditions are met, the PCM energizes the EGR
valve control solenoid to disable the EGR. The PCM
checks for a change in the oxygen sensor signal. If
the air-fuel mixture goes lean, the PCM will attempt
to enrichen the mixture. The PCM registers a diag­
nostic trouble code (DTC) if the EGR system has
failed or degraded. After registering a DTC, the PCM
turns the CHECK ENGINE lamp on. Illumination of
this lamp indicates the need for immediate service.
Note that the CHECK ENGINE lamp will illuminate
initially for approximately two seconds each time the
ignition key is turned to the ON position. This is
done for a bulb test.
For a complete operational description of all
DTC's, for accessing a DTC and for erasing a
DTC, refer to On-Board Diagnostics. This can
be found in the General Diagnosis sections of
Group 14, Fuel System. For numeric flash lamp
code charts for emission related components,
refer to Diagnostic Trouble Code (DTC). This