SsangYong Musso. Manual - part 107

1F-12 ENGINE CONTROLS

SSANGYONG  Y158

Severe Vibration

The Misfire diagnostic measures small changes in the
rotational speed of the crankshaft. Severe driveline
vibrations in the vehicle, such as caused by an exces-
sive amount of mud on the wheels, can have the same
effect on crankshaft speed as misfire and, therefore, may
set DTC P0300.

Related System Faults

Many of the EOBD system diagnostics will not run if
the Engine Control Module (ECM) detects a fault on a
related system or component. One example would be
that if  the ECM detected a misfire fault, the diagnostics
on the catalytic converter would be suspended until the
misfire fault was repaired. If the misfire fault is severe
enough, the catalytic converter can be damaged due to
overheating and will never set a Catalyst DTC until the
misfire fault is repaired and the Catalyst diagnostic is
allowed to run to completion. If this happens, the
custom-er may have to make two trips to the dealership
in order to repair the vehicle.

SERIAL DATA COMMUNICATIONS

Keyword 2000 Serial Data Communications

Government regulations require that all vehicle
manufacturers establish a common communication sys-
tem. This vehicle utilizes the “KWP2000” communication
system. Each bit of information can have one of two
lengths: long or short. This allows vehicle wiring to be
reduced by transmitting and receiving multiple signals
over a single wire. The messages carried on KWP2000
data streams are also prioritized. If two messages at-
tempt to establish communications on the data line at
the same time, only the message with higher priority
will continue. The device with the lower priority message
must wait. The most significant result of this regulation
is  that it provides scan tool manufacturers with the
capability to access data from any make or model vehicle
that is sold.

The data displayed on the other scan tool will appear
the same, with some exceptions. Some scan tools will
only be able to display certain vehicle parameters as
values that are a coded representation of the true or
actual value. On this vehicle, the scan tool displays the
actual values  for vehicle parameters. It will not be
necessary to perform any conversions from coded values
to actual values.

EURO ON-BOARD DIAGNOSTIC
(EOBD)

On-Board Diagnostic Tests

A diagnostic test is a series of steps, the result of which
is a pass or fail reported to the diagnostic executive.

When a diagnostic test reports a pass result, the diag-
nostic executive records the following data:

•••••

The diagnostic test has been completed since the
last ignition cycle.

•••••

The diagnostic test has passed during the current
ignition cycle.

•••••

The fault identified by the diagnostic test is not cur-
rently active.

When a diagnostic test reports a fail result, the diagnos-
tic executive records the following data:

•••••

The diagnostic test has been completed since the
last ignition cycle.

•••••

The fault identified by the diagnostic test is currently
active.

•••••

The fault has been active during this ignition cycle.

•••••

The operating conditions at the time of the failure.

Remember, a fuel trim Diagnostic Trouble Code (DTC)
may be triggered by a list of vehicle faults. Make use of
all information available (other DTCs stored, rich or lean
condition, etc.) when diagnosing a fuel trim fault.

COMPREHENSIVE COMPONENT
MONITOR DIAGNOSTIC
OPERATION

Comprehensive component monitoring diagnostics are
required to monitor emissions-related input and output
powertrain components.

Input Components

Input components are monitored for circuit continuity
and out-of-range values. This includes rationality check-
ing. Rationality checking refers to indicating a fault when
the signal from a sensor does not seem reasonable,
i.e.

Throttle Position (TP) sensor that indicates high throttle
position at low engine loads or Mass Air Flow (MAF)
voltage. Input components may include, but are not lim-
ited to, the following sensors:

•••••

Vehicle Speed Sensor (VSS).

•••••

Crankshaft Position (CKP) sensor.

•••••

Throttle Position (TP) sensor.

•••••

Engine Coolant Temperature (ECT) sensor.

•••••

Camshaft Position (CMP) sensor.

•••••

Mass Air Flow (MAF) sensor or Manifold Absolute
Pressure (MAP) sensor.

In addition to the circuit continuity and rationality check,
the ECT sensor is monitored for its ability to achieve a
steady state temperature to enable closed loop fuel con-
trol.

Output Components

Output components are diagnosed for proper response
to control module commands. Components where func-
tional monitoring is not feasible will be monitored for cir-
cuit continuity and out-of-range values if applicable.

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Output components to be monitored include, but are
not limited to the following circuit:

•••••

Control module controlled Evaporative Emission
(EVAP) Canister Purge Valve.

•••••

A/C relays.

•••••

Cooling fan relay.

•••••

Malfunction Indicator Lamp (MIL) control.

Refer to “Engine Control Module” and the sections on
Sensors in General Descriptions.

Passive and Active Diagnostic Tests

A passive test is a diagnostic test which simply monitors
a vehicle system or component. Conversely, an active
test, actually takes some sort of action when performing
diagnostic functions, often in response to a failed pas-
sive test.

Intrusive Diagnostic Tests

This is any on-board test run by the Diagnostic Manage-
ment System which may have an effect on vehicle per-
formance or  emission levels.

Warm-Up Cycle

A warm-up cycle means that engine at temperature must
reach a minimum of 70 °C (160 °F) and rise at least 22
°C (40 °F) over the course of a trip.

Freeze Frame

Freeze Frame is an element of the Diagnostic Manage-
ment System which stores various vehicle information
at the moment an emissions-related fault is stored in
memory and when the MIL is commanded ON. These
data can help to identify the cause of a fault.

Failure Records

Failure Records data is an enhancement of the EOBD
Freeze Frame feature. Failure Records store the same

vehicle information as does Freeze Frame, but it will
store that information for any fault which is stored in on-
board memory, while Freeze Frame stores information
only for emission-related faults that command the MIL
ON.

Common EOBD Terms

Diagnostic

When used as a noun, the word diagnostic refers to any
on-board test run by the vehicle’s Diagnostic Manage-
ment  System. A diagnostic is simply a test run on a
system or component to determine if the system or
component is operating according to specification.

There are many diagnostics, shown in the following list:

•••••

Misfire.

•••••

Oxygen sensors (O2S)

•••••

Fuel Trim

•••••

Evaporative Emission

•••••

Catalyst monitoring

Enable Criteria

The term “enable criteria” is engineering language for
the conditions necessary for a given diagnostic test to
run. Each diagnostic has a specific list of conditions
which must be met before the diagnostic will run. “Enable
criteria” is another way of saying “conditions required.”

The enable criteria for each diagnostic is listed on the
first page of the Diagnostic Trouble Code (DTC) descrip-
tion under the heading “Conditions for Setting the DTC.”
Enable criteria varies with each diagnostic and typically
includes, but is not limited to the following items:

•••••

Engine speed.

•••••

Vehicle speed

•••••

Engine Coolant Temperature (ECT)

•••••

Mass Air Flow (MAF) or Manifold Absolute Pressure
(MAP)

•••••

Intake Air Temperature (IAT)

•••••

Throttle Position (TP)

•••••

Canister Purge Valve Status

•••••

Fuel trim

•••••

A/C ON

Trip

Technically, a trip is a key-on run key-off cycle in which
all the enable criteria for a given diagnostic are met, al-
lowing the diagnostic to run. Unfortunately, this concept
is not quite that simple. A trip is official when all the en-
able criteria for a given diagnostic are met. But because
the enable criteria vary from one diagnostic to another,
the definition of trip varies as well. Some diagnostics
are run when the vehicle is at operating temperature,
some when the vehicle first starts up; some require that
the vehicle cruise at a steady highway speed, some run
only  when the vehicle is at idle. Some run only
immediately following a cold engine start-up.

A trip then, is defined as a key-on run-key off cycle in
which the vehicle is operated in such a way as to satisfy
the enable criteria for a given diagnostic, and this diag-
nostic will consider this cycle to be one trip. However,
another diagnostic with a different set of enable criteria
(which were not met) during this driving event, would not
consider it a trip. No trip will occur for that particular
diagnostic until the vehicle is driven in such a way as to
meet all the enable criteria.

Diagnostic Information

The diagnostic charts and functional checks are de-
signed to  locate a faulty circuit or component through a
process of logical decisions. The charts are prepared
with the requirement that the vehicle functioned correct-
ly at the time of assembly and that there are not multiple
faults present.

There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complimented
by the diagnostic procedures contained in this manual.
The  language of communicating the source of the

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malfunction is a system of diagnostic trouble codes.

When a malfunction is detected by the control module,
a DTC is set, and the Malfunction Indicator Lamp (MIL)
is illuminated.

Malfunction Indicator Lamp (MIL)

The Malfunction Indicator Lamp (MIL) is required by Euro
On-Board Diagnostics (EOBD) to illuminate under a strict
set of guidelines.

Basically, the MIL is turned ON when the Engine Control
Module (ECM) detects a DTC that will impact the vehicle
emissions.

The MIL is under the control of the Diagnostic Execu-
tive. The MIL will be turned ON if an emissions-related
diagnostic test indicates a malfunction has occurred. It
will stay ON until the system or component passes the
same test for three consecutive trips with no emissions
related faults.

Extinguishing the MIL

When the MIL is ON, the Diagnostic Executive will turn
OFF the MIL after three consecutive trips that a “test
passed” has been reported for the diagnostic test that
originally caused the MIL to illuminate. Although the MIL
has been turned OFF, the DTC will remain in the ECM
memory (both Freeze Frame and Failure Records) until
forty (40) warm-up cycles after no faults have been com-
pleted.

If the MIL was set by either a fuel trim or misfire-related
DTC, additional requirements must be met. In addition
to the requirements stated in the previous paragraph,
these requirements are as follows:

•••••

The diagnostic tests that are passed must occur with
375 rpm of the rpm data stored at the time the last
test failed.

•••••

Plus or minus ten percent of the engine load that
was  stored at the time the last test failed. Similar
engine  temperature conditions (warmed up or
warming up) as those stored at the time the last test
failed.

Meeting these requirements ensures that the fault which
turned ON the MIL has been corrected.

The MIL is on the instrument panel and has the following
functions:

•••••

It informs the driver that a fault affecting the vehicle’s
emission levels has occurred and that the vehicle
should be taken for service as soon as possible.

•••••

As a system check, the MIL will come ON with the
key ON and the engine not running. When the engine
is started, the MIL will turn OFF.

•••••

When the MIL remains ON while the engine is run-
ning, or when a malfunction is suspected due to a
driveability or emissions problem, an EOBD System
Check must be performed. The procedures for these
checks are given in EOBD System Check. These
checks will expose faults which may not be detected
if other diagnostics are performed first.

Data Link Connector (DLC)

The provision for communicating with the control mod-
ule is  the Data Link Connector (DLC). The DLC is used
to connect to a scan tool. Some common uses of the
scan tool are listed below:

•••••

Identifying stored DTCs.

•••••

Clearing DTCs.

•••••

Performing output control tests.

•••••

Reading serial data.

DTC TYPES

Each Diagnostic Trouble Code (DTC) is directly related
to a diagnostic test. The Diagnostic Management Sys-
tem sets DTCs based on the failure of the tests during a
trip or trips. Certain tests must fail two consecutive trips
before the DTC is set. The following are the two types of
DTCs and the characteristics of those codes:

Type A

•••••

Emissions related.

•••••

Requests illumination of the Malfunction Indicator.

Lamp (MIL) of the first trip with a fail.

•••••

Stores a History DTC on the first trip with a fail.

•••••

Stores a Freeze Frame (if empty).

•••••

Stores a Fail Record.

•••••

Updates the Fail Record each time the diagnostic
test fails.

Type B

•••••

Emissions related.

•••••

“Armed” after one trip with a fail.

•••••

“Disarmed” after one trip with a pass.

•••••

Requests illumination of the MIL on the second con-
secutive trip with a fail.

•••••

Stores a History DTC on the second consecutive trip.

with a fail (The DTC will be armed after the first fail).

•••••

Stores a Freeze Frame on the second consecutive
trip with a fail (if empty).

Important: Only four Fail Records can be stored. Each
Fail Record is for a different DTC. It is possible that
there will not be Fail Records for every DTC if multiple
DTCs are set.

Reading Diagnostic Trouble Codes

The procedure for reading Diagnostic Trouble Code(s)
(DTC) is to use a diagnostic scan tool. When reading
DTC(s) , follow instructions supplied by tool manufactur-
er.

Clearing Diagnostic Trouble Codes

Important: Do not clear DTCs unless directed to do so
by the service information provided for each diagnostic
procedure. When DTCs are cleared, the Freeze Frame
and Failure Record data which may help diagnose an
intermittent fault will also be erased from memory. If the
fault that caused the DTC to be stored into memory has

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been corrected, the Diagnostic Executive will begin to
count the “warm-up” cycles with no further faults de-
tected, the DTC will automatically be cleared from the
Engine Control Module (ECM) memory.

To clear DTCs, use the diagnostic scan tool. When a
scan tool is not available.

Notice:  To prevent system damage, the ignition key
must be OFF when disconnecting or reconnecting bat-
tery power.

•••••

The power source to the control module. Examples:
fuse, pigtail at battery ECM connectors, etc.

•••••

The negative battery cable. (Disconnecting the nega-
tive battery cable will result in the loss of other on-
board memory data, such as preset radio tuning.)

PRIMARY SYSTEM-BASED
DIAGNOSTICS

There are primary system-based diagnostics which
evaluate the system operation and its effect on vehicle
emissions. The primary system-based diagnostics are
listed below with a brief description of the diagnostic
function:

Oxygen Sensor Diagnosis

The fuel control oxygen sensor (O2S) is diagnosed for
the following conditions:

•••••

Slow response.

•••••

Response time (time to switch Rich/Lean or Lean/
Rich).

•••••

Inactive signal (output steady at bias voltage approxi-
mately 450 mv).

•••••

Signal fixed high.

•••••

Signal fixed low.

•••••

Heater performance (time to activity on cold start).

•••••

Signal fixed low during steady state conditions or
power enrichment (hard acceleration when a rich mix-
ture should be indicated).

•••••

Signal fixed high during steady state conditions or
de-celeration mode (deceleration when a lean mixture
should be indicated).

If the O2S pigtail wiring, connector or terminal are dam-
aged, the entire O2S assembly must be replaced. Do
not attempt to repair the wiring, connector or terminals.
In order for the sensor to function properly, it must have
clean reference air provided to it. This clean air refer-
ence is  obtained by way of the O2S wire(s). Any attempt
to repair the wires, connector or terminals could result
in the obstruction of the reference air and degrade the
O2S performance.

Misfire Monitor Diagnostic Operation

The misfire monitor diagnostic is based on crankshaft
rotational velocity (reference period) variations. The En-
gine Control Module (ECM) determines crankshaft rota-
tional  velocity using the Crankshaft Position (CKP)

sensor and the Camshaft Position (CMP) sensor. When
a cylinder misfires, the crankshaft slows down momen-
tarily.

By monitoring the CKP and CMP sensor signals, the
ECM can calculate when a misfire occurs.

For a non-catalyst damaging misfire, the diagnostic will
be required to monitor a misfire present for between 1000
engine revolutions.

For catalyst-damaging misfire, the diagnostic will re-
spond to  misfire within 200 engine revolutions.

Rough roads may cause false misfire detection. A rough
road will cause torque to be applied to the drive wheels
and drive train. This torque can intermittently decrease
the crankshaft rotational velocity. This may be falsely
detected as a misfire.

ECM compensates about rough road without any addi-
tional sensor. It means that ECM could distinguish the
actual misfire or rough road variation.

Misfire Counters

Whenever a cylinder misfires, the misfire diagnostic
counts the misfire and notes the crankshaft position at
the time the misfire occurred. These “misfire counters”
are basically a file on each engine cylinder. A current
and a history misfire counter are maintained for each
cylinder. The misfire current counters (Misfire Cur #1-6)
indicate the number of firing events out of the last 200
cylinder firing events which were misfires. The misfire
current counter will display real time data without a mis-
fire DTC stored. The misfire history counters (Misfire
Hist #1-6) indicate the total number of cylinder firing
events which were misfires. The misfire history counters
will display 0 until the misfire diagnostic has failed and
a DTC P0300 is set. Once the misfire DTC P0300 is
set, the misfire history counters will be updated every
200 cylinder firing events. A misfire counter is maintained
for each cylinder.

If the misfire diagnostic reports a failure, the diagnostic
executive reviews all of the misfire counters before re-
porting a DTC. This way, the diagnostic executive re-
ports the most current information.

When crankshaft rotation is erratic, a misfire condition
will be detected. Because of this erratic condition, the
data that is collected by the diagnostic can sometimes
incorrectly identify which cylinder is misfiring.

Use diagnostic equipment to monitor misfire counter data
on EOBD compliant vehicles. Knowing which specific
cylinder(s) misfired can lead to the root cause, even
when dealing with a multiple cylinder misfire. Using the
information in the misfire counters, identify which cylin-
ders are misfiring. If the counters indicate cylinder num-
ber 1 misfired, look for a circuit or component related to
cylinders number 1.

The misfire diagnostic may indicate a fault due to a tem-
porary fault not necessarily caused by a vehicle emis-
sion system malfunction. Examples include the following