Emission Control System - Chrysler 1998 Voyager Service Manual

NS/GS

EMISSION CONTROL SYSTEM—

2.0L ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . 9
EXHAUST EMISSION CONTROLS—
2.5L DIESEL ENGINE . . . . . . . . . . . . . . . . . . . 5
ON-BOARD DIAGNOSTICS—2.5L DIESEL ENGINE
GENERAL INFORMATION
SYSTEM DESCRIPTION—
2.5L DIESEL ENGINE . . . . . . . . . . . . . . . . . . . 1
GENERAL INFORMATION
SYSTEM DESCRIPTION—2.5L DIESEL ENGINE
The 2.5L diesel Powertrain Control Module (PCM)
monitors and controls many different circuits in the
fuel injection pump and engine systems. If the PCM
senses a problem with a monitored circuit that indi-
cates an actual problem, a Diagnostic Trouble Code
(DTC) will be stored in the PCM's memory, and even-
tually will illuminate the Diesel Glow Plug lamp con-
stantly while the key is on. If the problem is
repaired, or is intermittent, the PCM will erase the
DTC after 40 warm-up cycles. A warm-up cycle con-
sists of starting the vehicle when the engine is cold,
then the engine to warms up to a certain tempera-
ture, and finally, the engine temperature falls to a
normal operating temperature, then the key is
turned off.
Certain criteria must be met for a DTC to be
entered into PCM memory. The criteria may be a
specific range of engine rpm, engine or fuel tempera-
ture and/or input voltage to the PCM. A DTC indi-
cates that the PCM has identified an abnormal
signal in a circuit or the system. A DTC may indicate
the result of a failure, but never identify the failed
component directly.
There are several operating conditions that the
PCM does not monitor and set a DTC for. Refer to
the following Monitored Circuits and Non–Monitored
Circuits in this section.
EMISSION CONTROL SYSTEM
CONTENTS
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EMISSION CONTROL SYSTEM
ON-BOARD DIAGNOSTICS—
2.5L DIESEL ENGINE . . . . . . . . . . . . . . . . . . . 1
INDEX
DESCRIPTION AND OPERATION
DIAGNOSTIC TROUBLE CODES . . . . . . . . . . . . 2
MONITORED CIRCUITS
The PCM can detect certain problems in the elec-
trical system.
Open or Shorted Circuit – The PCM can deter-
mine if sensor output (which is the input to PCM) is
within proper range. It also determines if the circuit
is open or shorted.
Output Device Current Flow – The PCM senses
whether the output devices are electrically connected.
If there is a problem with the circuit, the PCM
senses whether the circuit is open, shorted to ground
(–), or shorted to (+) voltage.
NON–MONITORED CIRCUITS
The PCM does not monitor the following circuits,
systems or conditions that could have malfunctions
that result in driveability problems. A DTC will not
be displayed for these conditions.
Fuel Pressure: Fuel pressure is controlled by the
fuel injection pump. The PCM cannot detect prob-
lems in this component.
Cylinder Compression: The PCM cannot detect
uneven, low, or high engine cylinder compression.
Exhaust System: The PCM cannot detect a
plugged, restricted or leaking exhaust system.
Fuel Injector Malfunctions: The PCM cannot
determine if the fuel injector is clogged, or the wrong
injector is installed. The fuel injectors on the diesel
engine are not controlled by the PCM, although a
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