The PCM compares input signal voltages from each input device with established high and low limits for the device.
If the input voltage is not within limits and other criteria are met, the PCM stores a diagnostic trouble code in mem-
ory. Other diagnostic trouble code criteria might include engine RPM limits or input voltages from other sensors or
switches that must be present before verifying a diagnostic trouble code condition.

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EVAPORATIVE EMISSIONS

DIAGNOSIS AND TESTING

OBD II Monitor Information

Comprehensive Components

Monitor

Major Monitors Non Fuel

Control & Non Misfire

Major Monitors Fuel Control &

misfire

(Includes All Engine Hardware

Sensor, Switches, Solenoids,

etc.)

(Monitors Entire Emission

System)

(Monitors Entire System)

Most are one trip Faults

Most are Two Trips Faults

Two Trip Faults

Usually Turns on The Mill and

Sets DTC After One Failure

Turns On The Mil and Sets

DTC after Two Consecutive

Failure

The Mil and Sets DTC After Two

Consecutive Failure

Priority 3

Priority 1 or 3

Priority 2 or 4

All Checked For Continuity

Done Stop Test = Yes

Fuel Control Monitor

Open

Oxygen Sensor Heater

Monitors Fuel Control

Short To Ground

Oxygen Sensor Response

System For:

Short To Voltage

Catalytic Converter

Fuel System Lean

Inputs Checked For Rationality

Efficiency Except EWMA

Fuel System Rich

Outputs Checked For
Functionality

up to 6 test per trip and a one
trip fault (SBEC) and two trip
fault on (JTEC)

Requires 3 Consecutive Fuel

System Good Trips to Extinguish

the MIL

EGR System

Misfire Monitor

Evaporative Emission System
(purge and leak)

Monitors for Engine Misfire At:

Non-LDP

4 X 1000 RPM Counter (4000

Revs) (Type B)

LDP

**200 X 3 (600) RPM counter

(Type A)

Requires 3 Consecutive Global

Good Trips to Extinguish the

MIL*

Requires 3 Consecutive Global
Good Trips to Extinguish the
MIL*

Requires 3 Consecutive Global
Good Trips to Extinguish the MIL

*40 Warm Up Cycles are

required to erase DTCs after the

MIL has been extinguished

** Type A misfire is a one trip

failure on pre-1999, 2 trip failure

on 1999 and later. The MIL will

illuminate at the first or second

failure, based on MY.

OBD II MONITOR RUN PROCESS

The following procedure has been established to assist Chrysler Dealer Technicians in the field with enabling and
running OBD II Monitors. The order listed in the following procedure is intended to allow the technician to effectively
complete each monitor and to set the CARB Readiness Status in the least time possible.

NOTE: A. Once the monitor run process has begun, do not turn off the ignition. By turning the ignition key
off, monitor enabling conditions will be lost. NVLD Monitor runs after key off.B. By performing a Battery
Disconnect, or Selecting Erase DTCs, the CARB Readiness and all additional OBD II information will be
cleared.

Monitor Preliminary Checks:

1. Plug a SCAN TOOL into the vehicle’s Data Link Connector (DLC).

EVAPORATIVE EMISSIONS

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2. Turn the ignition, KEY ON - ENGINE OFF. Watch for MIL lamp illumination during the bulb check. MIL lamp must

have illuminated, if not, repair MIL lamp.

3. On the SCAN TOOL Select #1Stand-alone.

4. Select #1 1998-2004 Diagnostics.

5. Select #1 Engine.

6. Select #2 DTCs and Related Functions.

7. Select #1 Read DTCs.

•

Verify that No Emissions Related DTCs are Present.

•

* If an Emissions DTC is Present, the OBD II Monitors may not run and the CARB Readiness will not update.

•

The Emissions related DTC, will need to be repaired, then cleared. By clearing DTCs, the OBD Monitors will
need to be run and completed to set the CARB Readiness Status.

8. Return to Engine Select Function Menu and Select #9, OBD II Monitors.

9. Select #3 CARB Readiness Status.

Do all the CARB Readiness Status Locations read YES?.

•

*YES, then all monitors have been completed and this vehicle is ready to be I/M or Emission Tested.

•

*NO, then the following procedure needs to be followed to run/complete all available monitors.

NOTE: A. Only the monitors, which are not YES in the CARB Readiness Status, need to be completed.B.
Specific criteria need to be met for each monitor. Each monitor has a Pre-Test screen to assist in running
the monitor. For additional information, refer to the DaimlerChrysler Corporation Technical Training Work-
book titled On Board Diagnostics: OBD II/EOBD, part number 81-699-01050.C. The most efficient order to
run the monitors has been outlined below, including suggestions to aid the process.

Natural Vacuum Leak Detection with Purge Monitor

This monitor requires a cool down cycle, usually an overnight soak for at least 8 hours without the engine running.
The ambient temperature must decrease overnight - parking the vehicle outside is advised. To run this test the fuel
level must be between 15-85% full. For the monitor run conditions select the EVAP MON PRE-TEST in the SCAN
TOOL, OBD II Monitors Menu.The Purge monitor will run if the small leak test reports a pass. Criteria for NVLD
monitor:

•

Engine off time greater than @ one hour.

•

Fuel Level between 15% and 85 %.

•

Start Up ECT and IAT within 10 C (18 F).

•

Vehicle started and run until Purge Monitor reports a result.

NOTE: If the vehicle does not report a result and the conditions where correct. It may take up to two weeks
to fail the small leak monitor. DO NOT use this test to attempt to determine a fault. Use the appropriate
service information procedure for finding a small leak. If there are no faults and the conditions are correct
this test will run and report a pass. Note the Small leak test can find leaks less than 10 thousands of an
inch. If a small leak is present it takes approximately one week of normal driving to report a failure.

Catalyst / O2 Monitor

With NGC, Catalyst and O2 Monitor information are acquired and processed at the same time. Most vehicles will
need to be driven at highway speed (< 50 mph) for a few minutes.Some trucks run the monitor at idle in drive. If the
vehicle is equipped with a manual transmission, using 4th gear may assist in meeting the monitor running criteria.
For the monitor run conditions, select the BANK 1 CAT MON PRE-TEST in the SCAN TOOL, OBD II Monitors
Menu.

EGR Monitor

The EGR monitor now runs in a closed throttle decel or at idle on a warm vehicle. However, it is necessary to
maintain the TPS, Map and RPM ranges to allow the monitor to complete itself. For the monitor run conditions,
select the EGR PRE-TEST in the SCAN TOOL, OBD II Monitors Menu.

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EVAPORATIVE EMISSIONS

O2 Sensor Heater Monitor

This monitor is now continuously running once the heaters are energized. Pass information will be processed at
power down. For the monitor run conditions, select the O2S HEATER MON PRE-TEST in the SCAN TOOL, OBD II
Monitors Menu.

SPECIFICATIONS

TORQUE - EVAP SYSTEM

DESCRIPTION

N·m

Ft. Lbs.

In. Lbs.

EVAP Canister Mounting

Nuts

EVAP Canister Mounting

Bracket-to-Frame Bolts

125

NVLD Pump Mounting

Bolts

NVLD Pump Filter

Mounting Bolt

SOLENOID-EVAP/PURGE

DESCRIPTION

The duty cycle EVAP canister purge solenoid (2) is
located in the engine compartment attached to a
bracket.

OPERATION

The Powertrain Control Module (PCM) operates the solenoid.

During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When
de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.

The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During
closed loop operation, the PCM energizes and de-energizes the solenoid 5 or 10 times per second, depending upon
operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the
amount of time the solenoid energizes. The PCM adjusts solenoid pulse width based on engine operating condition.

EVAPORATIVE EMISSIONS

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