Description And Operation; Malfunction Indicator Lamp (Mil); State Display Test Mode; Circuit Actuation Test Mode - Dodge 2000 DURANGO Service Manual

25 - 2 EMISSION CONTROL SYSTEMS
DESCRIPTION AND OPERATION (Continued)
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).
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 (check engine lamp).

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:
• PCM does not detect the malfunction for 3 con-
secutive trips (except misfire and Fuel system Moni-
tors).
• 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
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
375 RPM of and within
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

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.

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.
OBTAINING DTC's
WARNING: APPLY PARKING
BLOCK WHEELS BEFORE PERFORMING ANY TEST
ON AN OPERATING ENGINE.
(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.
DN
BRAKE AND/OR