1993 DODGE TRUCK service indicator

•

EMISSION
CONTROL
SYSTEMS
25
- 1
CONTENTS

page page

AIR INJECTION
SYSTEM-o
9L
HDC-GAS EVAPORATIVE EMISSION CONTROLS
6
ENGINE
15
EXHAUST EMISSION CONTROLS
10

COMPONENT
REMOVAL/INSTALLATION
17
GENERAL INFORMATION
1

GENERAL
INFORMATION

Throughout this group, references are made
to
par­
ticular vehicle models
by
alphabetical designation
or

by the particular vehicle nameplate.
A
chart showing a breakdown
of
alphabetical designations
is
included
in
the
Introduction section
at
the
beginning
of
this
manual.
The 5.9L (V-8) gas powered engine will
be
referred
to
in
this group
as
either the: LDC (Light Duty Cy­ cle)
or
HDC (Heavy Duty Cycle) engine.
The
HDC
engine can
be
easily identified
by
the
use
of
an en­

gine mounted
air
injection pump. The 3.9L/5.2L/5.9L
LDC engine will not use
an
air
injection pump.
Maintenance requirements for LDC and HDC emis­
sion systems differ because
of
different load
and
op­
erating conditions. This section will cover emission control systems
for

the 3.9L (V-6), 5.2L (V-8), 5.9L LDC (V-8), 5.9L HDC (V-8) and 5.9L (in-line six cylinder) diesel engines.

SERVICE
REMINDER INDICATOR
(SRI)
LIGHT
The instrument panel mounted SRI light was for­
merly referred
to as the
emission maintenance
re­
minder (EMR) light.
It is
used with 5.9L HDC-gas
powered engines only.
It is
not
used with diesel
en­
gines.

The SRI system
is
incorporated into the powertrain
control module (PCM)
(the
PCM
was
formerly
re­

ferred
to as the
engine controller
or
SBEC).
The

PCM records
the
vehicles mileage and stores
it
into
memory every
8
miles. At that time, the PCM checks
for the 60,000 and 82,500 mileage trip points. When
the current mileage matches one
of
the above men­
tioned trip points,
the
SRI light
is
activated.
The following parts are
to
be replaced
at
either the
indicated mileage
or
when the SRI light remains
on

when the key
is in
the ON position. After performing
the required maintenance,
the
SRI light must
be
re­ set
to
turn the light
off.

96,000
km
(60,000 miles):
• Replace EGR Valve
• Clean EGR passage • Replace PCV Valve
132,000
km
(82,500 miles):
• Replace Oxygen Sensor
Refer
to
Group
0,
Lubrication and Maintenance
for

all required maintenance schedules.
Failure
to
perform
the
required maintenance
and

only reset the SRI light may be
a
violation of federal
law. Only after performing
the
required mainte­
nance, should the SRI light
be
reset.

RESETTING
SRI
LIGHT
(1) Connect
the
DRB
II
scan tool
to
the
data link
connector (Fig.
1)
in
the engine compartment.
TORQUE CONVERTER
CLUTCH RELAY
A/C
CLUTCH RELAY
.
STARTER RELAY

AUTO
SHUTDOWN RELAY FUEL PUMP RELAY DATA LINK
CONNECTOR POWERTRAIN
CONTROL
MODULE
J9314-164

Fig.
1
Data
Link
Connector
(2) Refer
to
DRB
II
scan tool operation
in
the ap­

propriate Powertrain Diagnostic Procedures manual. (3) Reset SRI light.

VEHICLE
EMISSION CONTROL INFORMATION
(VECI)
LABEL
All vehicles equipped with
a
gasoline powered
en­

gine have
a
VECI label. The 3.9L/5.2L/5.9L LDC-gas powered engine will
have
a
label that combines both emission control
in­

formation and vacuum hose routing.
EMISSION CONTROL
SYSTEMS

•

EMISSION
CONTROL
SYSTEMS
25 - 11 • The electrical solenoid portion of the EET is not
energized.
• The engine back pressure entering the EGR valve
inlet is strong enough to close the transducer bleed
valve.
If back pressure is not strong enough to close the
transducer bleed valve, the transducer will bleed off the vacuum preventing EGR operation.
When the electrical solenoid portion of the EET is
de-energized by the powertrain control module (PCM), vacuum flows to the transducer. The trans­
ducer is connected to the engine exhaust system by a small hose that connects to the base of the EGR
valve.
The vacuum section of the transducer is controlled
by exhaust system back pressure. When back pres­ sure is high enough it will close a bleed valve in the
transducer allowing vacuum to actuate the EGR
valve. If back pressure does not close the bleed valve,
vacuum will be bled off.
For more information, refer to Group 14, Fuel Sys­

tems.
Refer to the Component Removal/Installation sec­
tion of this group for EGR valve replacement proce­
dures.

EGR SYSTEM ON-BOARD DIAGNOSTICS
(CALIFORNIA VEHICLES
ONLY)

The powertrain control module (PCM) performs an
On-Board Diagnostic (OBD) check of the EGR system
on all California vehicles. The diagnostic system uses
the electric EGR transducer (EET) for the system

tests.

The OBD check activates only during selected en­
gine/driving conditions. When the conditions are met,
the PCM energizes the EET 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 diagnostic trouble code (DTC) if the EGR system has failed or degraded. After registering a

DTC,
the PCM turns the malfunction indicator
lamp (MIL) on. (The malfunction indicator lamp was formerly referred to as the check engine lamp). The
malfunction indicator lamp indicates the need for im­
mediate service.
If a malfunction is indicated by the malfunction in­
dicator lamp and a DTC for the EGR system was set,
check for proper operation of EGR system. Use the
following: System Test, EGR Gas Flow Test and EGR
Diagnosis Chart.
If the EGR system tests properly, check the system
using the DRB II scan tool. For use of the DRB II,
refer to the appropriate Powertrain Diagnostics Pro­ cedure service manual. EGR SYSTEM SERVICE
A malfunctioning EGR system can cause engine
spark knock, sags or hesitation, rough idle, engine
stalling and poor driveability. To be sure of proper
operation of the EGR system, inspect all passages for
blockage. Check moving parts for binding. Inspect
the complete system for leaks. Replace system com­ ponents or hoses that are leaking.
Inspect all hose connections between throttle body,
intake manifold, EGR valve and EGR purge solenoid.
Replace any vacuum harness components that are
leaking or damaged. Refer to EGR Control System Test and EGR Gas
Flow Test to check EGR System operation.
EGR GAS FLOW TEST (1) Disconnect hose from EGR valve and connect a
hand vacuum pump to EGR valve nipple. Apply a
minimum of 12 inches vacuum the valve.
(2) The engine should now idle roughly or stall. If
this occurs, the valve is performing correctly. Proceed
to Electric EGR Transducer Test.
(3) If the engine idle speed did not change, remove
the EGR valve and inspect the valve and the exhaust passage in the manifold for blockage. Repair as nec­
essary. If blockage is not present, replace the EGR
valve.
ELECTRIC EGR TRANSDUCER (EET)

TESTING ELECTRIC SOLENOID PORTION OF TRANSDUCER
(1) Bring the engine to normal operating tempera­

ture.
Operate at idle speed. Test the EET as follows: (2) Check vacuum at EET vacuum source. Discon­
nect the hose and attach a vacuum gauge to it.
(3) Vacuum should be a minimum of 15 inches:
• If vacuum is low, check the line for kinks, twists
or a loose connection at vacuum connector or intake
manifold.
• If vacuum is correct, remove gauge. Connect the
vacuum line and proceed to next step. (4) Check EET operation using the appropriate
Powertrain Diagnostic Procedures service manual.
Refer to this manual for use of the DRB II scan tool and repair EET as necessary.

TESTING VACUUM PORTION
OF
TRANSDUCER
(1) Disconnect the EET vacuum lines, back pres­
sure line and electrical connector. Remove trans­
ducer.
(2) Plug the EET EGR valve port.
(3) Apply 1-2 pounds air pressure to exhaust back
pressure port. Air pressure can be supplied with a
hand operated air pump or compressed air (regulated
to correct psi).
(4) Apply a minimum of 12 inches of vacuum to
vacuum supply port.
Replace the EET if it will not hold vacuum.