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Dodge Viper SRT-10 (ZB). Manual - part 399

OBD II Monitor Operation

Comprehensive

Major Monitors

Components

Non Fuel Control

Fuel Control

Monitor

& Non Misfire

& Misfire

Run constantly

Run Once Per Trip

Run constantly

Includes All Engine Hardware

Monitors Entire Emission

Monitors Entire System

•

Sensors, Switches,

System

Solenoids, etc.

Most are One Trip Faults –
Usually Turns On

Most are Two Trip Faults –
Turns On

Two Trip Faults –
Turns On

The MIL and Sets DTC After

One Failure

Two Consecutive Failures

Priority 3

Priority 1 or 3

Priority 2 or 4

All Checked For Continuity

Done Stop Testing = Yes

Fuel Control Monitor

Open

Monitors Fuel Control

Short To Ground

Oxygen Sensor Heater

System For:

Short To Voltage

Oxygen Sensor Response

Fuel System Lean
Fuel System Rich

Inputs Checked For

Requires 3 Consecutive

Rationality

Catalytic Converter

Fuel System Good Trips

Efficiency Except EWMA

Extinguish The MIL

Outputs Checked For

up to 6 tests per trip

Functionality

and a one trip fault (SBEC)
and a two-trip fault on JTEC

EGR System

Misfire Monitor

Evaporative Emission

Monitors For Engine Misfire

System

at:

(Purge and Leak)

4 X 1000 RPM Counter
(4000 Revs)

Non-LDP

(Type B)

**200 X 3 (600) RPM Counter

LDP

(Type A)

Requires 3 Consecutive

Global Good Trips

to Extinguish the MIL*

To Extinguish the MIL

*40 Warm Up Cycles are required to erase

**Type A misfire is a one

DTCs after the MIL has been extinguished.

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.

GENERAL INFORMATION

3.2.3

JTEC CONTROLLED REAR WHEEL
DRIVE VEHICLES

The following procedure has been established to

assist 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.

B. By performing a Battery Disconnect, or Selecting

Erase DTCs, the CARB Readiness and all addi-
tional OBD information will be cleared.

Monitor Preliminary Checks:

1. Plug scantool into the vehicle’s DLC.

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. With the scantool check for any DTCs

* Verify that No Emissions Related DTCs are
Present and MIL is not illuminated.
* If an Emissions DTC is Present and the MIL is
ON, the OBD II Monitors may not run and the
CARB Readiness will not update.
*The Emissions related DTC, which is causing
the MIL, will need to be repaired, then cleared.
By clearing DTCs, the OBD Monitors will need
to be run and completed to set the CARB Readi-
ness Status.
*Group 25 of the Service Manual can assist in
determining which faults will illuminate the
MIL Lamp.

With the scantool check for CARB Readiness Sta-
tus:
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 procedures will aid in
running and completing all available monitors.

MONTIOR RUN PROCESS

Outlined below is the Monitor Run Process, in-

cluding suggestions and tips in order to aid in the
process of meeting the enabling criteria to allow any
of these monitors to run.

*NOTE: The most efficient order has been
outlined below. The first two monitors have
very similar enable criteria. It is possible that
the Evaporative Leak Detection Monitor will
run during the O2 Sensor Heater Monitor.

1. O2 Sensor Heater Monitor

This monitor requires a cold start, usually an
overnight soak or parked for at least 8 hours
without the engine running. The engine coolant
temperature must be within 10 degrees of
ambient/battery temperature, and the sensed
Ambient (outside temperature) must be between
approximately 0° F and 100° F. For the monitor
run conditions,

2. Evaporative Leak Detection Monitor (If the

vehicle is equipped with an LDP system)
This monitor requires a cold start, usually an
overnight soak or parked for at least 8 hours
without the engine running. The engine coolant
temperature must be within 10 degrees of
ambient/battery temperature, and the sensed
Ambient (outside) Temperature must be between
approximately 40° F and 90° F. For the monitor
run conditions select the EVAP LEAK PRE-
TEST in the DRBIII

t, OBD II Monitors Menu.

3. Catalyst Monitor

The vehicle will need to be driven at highway
speed for a few minutes (approximately 35 to 40
mph for 2.5L and 4.0L engines, 50 to 60 mph for
all others). 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 CATALYST
PRE-TEST in the DRBIII

t, OBD II Monitors

Menu.

4. O2 Sensor Monitor

The vehicle will need to be driven for a period of
time (approximately 35 to 40 mph for 2.5L and
4.0L engines, 50 to 60 mph for all others) and
brought to a stop for a short period of time (with
the Automatic Transmission left in Drive. The
O2 Monitor will not run in Park or Neutral on an
Automatic Transmission equipped vehicle). For
the monitor run conditions, select the O2 SEN-
SOR PRE-TEST in the DRBIII

t, OBD II Moni-

tors Menu.

5. Purge Monitor

The Purge Free (PF) cells must update on the
PURGE FLOW PRE-TEST screen. For the en-
able conditions, select ‘‘F1’’ while looking at the
PURGE FLOW PRE-TEST screen. Similar Test
conditions as the O2 Sensor Monitor, that is,
Normal Operating Temperature, come to a stop
while leaving the Automatic Transmission in
Drive (not Park or Neutral). The Purge Flow
Monitor will attempt to run every OTHER

GENERAL INFORMATION

Throttle Closure. If all of the parameters are met
and it still does not run, with your foot firmly on
the Service Brake, slightly (1/4) open the Throt-
tle and quickly close the Throttle. This will allow
the Purge Free update to happen, and then the
Purge Flow Monitor will Run.

3.2.4

OTHER CONTROLS

CHARGING SYSTEM

The charging system is turned on when the

engine is started and ASD relay energized. When
the ASD relay is on, ASD output voltage is supplied
to the ASD sense circuit at the PCM. This voltage is
connected in some cases, through the PCM and
supplied to one of the generator field terminals
(Gen Source +). All others, the Generator field is
connected directly to the ASD output voltage. The
amount of current produced by the generator is
controlled by the Electronic Voltage Regulator
(EVR) circuitry, in the PCM. Battery temperature is
determined either by IAT, Ambient or Battery tem-
perature sensor. This temperature along with
sensed line voltage is used by the PCM to vary
battery charging. This is accomplished by cycling
the path to ground to the other generator field
terminal (Gen field driver).

LEAK DETECTION PUMP SYSTEM

LEAK DETECTION PUMP OPERATION

The evaporative emission system is designed to

prevent the escape of fuel vapors from the fuel
system. Leaks in the system, even small ones, can
allow fuel vapors to escape into the atmosphere.
Government regulations require onboard testing to
make sure that the evaporative (EVAP) system is
functioning properly. The leak detection system
tests for EVAP system leaks and blockage. It also
performs self-diagnostics.

During self-diagnostics, the Powertrain Control

Module (PCM) first checks the Leak Detection
Pump (LDP) for electrical and mechanical faults. If
the first checks pass, the PCM then uses the LDP to
seal the vent valve and pump air into the system to
pressurize it. If a leak is present, the PCM will
continue pumping the LDP to replace the air that
leaks out. The PCM determines the size of the leak
based on how fast/long it must pump the LDP as it
tries to maintain pressure in the system.

EVAP LEAK DETECTION SYSTEM COMPONENTS
(FIGURE 1)

Service Port: Used with special tools like the
Miller

Evaporative

Emissions

Leak

Detector

(EELD) to test for leaks in the system.

EVAP Purge Solenoid: The PCM uses the EVAP
purge solenoid to control purging of excess fuel
vapors stored in the EVAP canister. It remains
closed during leak testing to prevent loss of pres-
sure.
EVAP Canister: The EVAP canister stores fuel
vapors from the fuel tank for purging.
EVAP Purge Orifice: Limits purge volume.
EVAP System Air Filter: Provides air to the LDP
for pressurizing the system. It filters out dirt while
allowing a vent to atmosphere for the EVAP system.

LEAK DETECTION PUMP (LDP) COMPONENTS

The main purpose of the LDP is to pressurize the

fuel system for leak checking. It closes the EVAP
system vent to atmospheric pressure so the system
can be pressurized for leak testing. The diaphragm
is powered by engine vacuum. It pumps air into the
EVAP system to develop a pressure of about 7.5

O (1/4) psi. A reed switch in the LDP allows the

PCM to monitor the position of the LDP diaphragm.
The PCM uses the reed switch input to monitor how
fast the LDP is pumping air into the EVAP system.
This allows detection of leaks and blockage.

The LDP assembly consists of several parts (Fig-

ure 2). The solenoid is controlled by the PCM, and it
connects the upper pump cavity to either engine
vacuum or atmospheric pressure. A vent valve
closes the EVAP system to atmosphere, sealing the
system during leak testing. The pump section of the
LDP consists of a diaphragm that moves up and
down to bring air in through the air filter and inlet
check valve, and pump it out through an outlet
check valve into the EVAP system.

The diaphragm is pulled up by engine vacuum,

and pushed down by spring pressure, as the LDP
solenoid turns on and off. The LDP also has a
magnetic reed switch to signal diaphragm position
to the PCM. When the diaphragm is down, the
switch is closed, which sends a 12 V (system volt-
age) signal to the PCM. When the diaphragm is up,

GENERAL INFORMATION

the switch is open, and there is no voltage sent to
the PCM. This allows the PCM to monitor LDP
pumping action as it turns the LDP solenoid on and
off.

LDP AT REST (NOT POWERED)

When the LDP is at rest (no electrical/vacuum)

the diaphragm is allowed to drop down if the
internal (EVAP system) pressure is not greater than
the return spring. The LDP solenoid blocks the
engine vacuum port and opens the atmospheric
pressure port connected through the EVAP system
air filter. The vent valve is held open by the dia-
phragm. This allows the canister to see atmospheric
pressure (Figure 3).

DIAPHRAGM UPWARD MOVEMENT

When the PCM energizes the LDP solenoid, the

solenoid blocks the atmospheric port leading
through the EVAP air filter and at the same time
opens the engine vacuum port to the pump cavity
above the diaphragm. The diaphragm moves up-
ward when vacuum above the diaphragm exceeds

spring force. This upward movement closes the vent
valve. It also causes low pressure below the dia-
phragm, unseating the inlet check valve and allow-
ing air in from the EVAP air filter. When the
diaphragm completes its upward movement, the
LDP reed switch turns from closed to open (Figure
4).

DIAPHRAGM DOWNWARD MOVEMENT

Based on reed switch input, the PCM de-

energizes the LDP solenoid, causing it to block the
vacuum port, and open the atmospheric port. This
connects the upper pump cavity to atmosphere
through the EVAP air filter. The spring is now able
to push the diaphragm down. The downward move-
ment of the diaphragm closes the inlet check valve
and opens the outlet check valve pumping air into
the evaporative system. The LDP reed switch turns
from open to closed, allowing the PCM to monitor
LDP pumping (diaphragm up/down) activity (Fig-
ure 5). During the pumping mode, the diaphragm
will not move down far enough to open the vent
valve.

GENERAL INFORMATION

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