2004 ISUZU TF SERIES ESP

6E–68 ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD)
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 ex ecutive.
When a diagnostic test reports a pass result, the
diagnostic ex ecutive 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
currently active.
When a diagnostic test reports a fail result, the
diagnostic ex ecutive 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.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Ex ecutive are listed as
follows:
Commanding the check engine lamp on and off
DTC logging and clearing
Current status information on each diagnostic
Diagnostic Information
The diagnostic charts and functional checks are
designed to locate a faulty circuit or component through
a process of logical decisions. The charts are prepared
with the requirement that the vehicle functioned
correctly 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 complemented
by the diagnostic procedures contained in this manual.
The language of communicating the source of the
malfunction is a system of diagnostic trouble codes.
When a malfunction is detected by the control module, a
diagnostic trouble code is set and the check engine
lamp is illumi nated.
Check Engine Lamp
The check engine lamp looks the same as the check
engine lamp you are already familiar with, the “Check
Engine” lamp.
Basically, the check engine lamp is turned on when the
ECM detects a DTC that will impact the vehicle
emissions.
When the check engine lamp remains “ON” while the
engine is running, or when a malfunction issuspected due to a driveability or emissions problem,
a Powertrain On-Board Diagnostic (OBD) System
Check must be performed. The procedures for these
checks are given in On-Board Diagnostic (OBD)
System Check. These checks will ex pose faults
which may not be detected if other diagnostics are
performed first.
Data Link Connector (DLC)
The provision for communication with the contorl
module is the Data Link Connector (DLC). It is located
behind the lower front instrument panel. The DLC is
used to connect to a Tech 2. Some common uses of the
Tech 2 are listed below:
Identifying stored Diagnostic Trouble Codes (DTCs).
Clearing DTCs.
Reading serial data.
Ver ify in g Veh icle Repair
Verification of vehicle repair will be more
comprehensive for vehicles with OBD system
diagnostic. Following a repair, the technician should
perform the following steps:
1. Review and record the Fail Records for the DTC
which has been diagnosed.
2. Clear DTC(s).
3. Operate the vehicle within conditions noted in the
Fail Records.
4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.
Following these steps is very important in verifying
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.

6E–74 ENGINE DRIVEABILITY AND EMISSIONS
TYPICAL SCAN DATA & DEFINITIONS (O2 SENSOR DATA)
Use the Typical Values Table only after the On-Board Diagnostic System Check has been completed, no DTC(s) were
noted, and you have determined that the on-board diagnostics are functioning properly. Tech 2 values from a
properly-running engine may be used for comparison with the engine you are diagnosing.
Condition : Vehicle stopping, engine running, air conditioning off & after warm-up (Coolant temperature approx imately
80 deg.)
Tech 2 ParameterUnitsIdle2000rpmDescription
1 Engine Speed rpm710 - 8751950 - 2050 The actual engine speed is measured by ECM from the
CKP sensor 58X signal.
2 Desired Idle Speed rpm825800 - 850 The desired engine idle speed that the ECM
commanding. The ECM compensates for various engine
loa ds.
3 Engine Coolant
Te mpe rature°C or °F80 - 9080 - 90 The ECT is measured by ECM from ECT sensor output
voltage. When the engine is normally warm upped, this
data displays approximately 80 °C or more.
4 Sta rt Up ECT (Engine
Coolant Temperature)°C or °FDepends on ECT
a t start-upDepends on ECT
at sta rt-upStart-up ECT is measured by ECM from ECT sensor
output voltage when engine is started.
5Inta ke Air
Temperature °C or °FDe pe nds on
ambient tempDepends on
ambient tempThe IAT is me asure d by ECM fro m IAT se nsor output
voltage. This data is changing by intake air temperature.
6 Sta rt Up IAT (Inta ke
Air Temperature)°C or °FDepends on IAT at
sta rt-upDepends on IAT at
start-upStart-up IAT is measured by ECM from IAT sensor output
voltage when engine is started.
7 Manifold Absolute
Pre ssurekPa31 - 3625 - 30The MAP (kPa ) is mea sured by ECM fro m MAP output
voltage. This data is changing by inlet manifold pressure.
8 Barometric Pressure kPaDe pe nds on
altitudeDepends on
altitudeThe ba ro me tric pressure is mea sure d by ECM from the
MAP se nsor o utput v o ltage monitore d during ke y up and
w ide o pe n thro ttle. This data is cha nging by a ltitude.
9 Throttle Position %02 - 4 Throttle position operating angle is measured by the
ECM from throttle position output voltage. This should
displa y 0% at idle a nd 99 - 100% at full throttle .
10 Calculated Air Flow g/s3.5 -4.508.0 - 10.0 This displays intake air amount. The mass air flow is
measured by ECM from the MAF sensor output voltage.
11 Air Fuel Ratio14.6:114.6:1 This displays the ECM commanded value. In closed
loo p, this sho uld no rmally be display ed a ro und 14.2:1 -
14.7:1.
12 Fuel System Status Open Loop/
Close LoopClo se Loo pClose Loop When the engine is first started the system is in “Ope n
Loop” operation. In “Open Loop”, the ECM igno res the
signal from the oxygen sensors. When various
conditions (ECT, time from start, engine speed & oxygen
sensor output) are met, the system enters “Closed Loop”
operation. In “Closed Loop”, the ECM calculates the air
fuel ratio based on the signal from the oxygen sensors.
13 Engine Load %2 - 55 - 10 This displays is calculated by the ECM form engine
speed and MAF sensor reading. Engine load should
increase with an increase in engine speed or air flow
amount.
14B1 O2 Sensor Ready
(Ba nk 1)Ye s / N oYe sYes This displays the status of the exhaust oxygen sensor.
This display will indicate “Ye s” when the ECM detects a
fluctuating oxygen sensor output voltage sufficient to
a llow clo se d loo p o pe ration. This will no t occur unle ss
the oxygen sensor is warmed up.
15B1S1 Status
(Bank 1 Sensor 1)Rich / Le anRich / LeanRich / Lean This displays dependent on the exhaust oxygen sensor
output voltage. Should fluctuate constantly “Rich” and
“Le an” in closed loop.
16 Fuel Trim Learned Yes/NoYe sYes When conditions are appropriate for enabling long term
fue l trim corrections, fue l trim le a rn will display “Ye s”.
This indica te s tha t the lo ng term fue l trim is respo nding
to the short te rm fue l trim. If the fue l trim le an displa y s
“No”, then long term fuel trim will not respond to changes
in short te rm fuel trim.

ENGINE DRIVEABILITY AND EMISSIONS 6E–75
17 Fuel Trim Ce ll15 - 201 - 2 This displays dependent on engine speed and calculated
intake air flow reading. A plot of engine speed versus
inta ke a ir flo w a mo unt is div ide d into the ce lls. Fuel trim
ce ll indica te s w hich cell is currently a ctiv e.
18B1S1 O2 Sensor
(Bank1 Sensor 1)mV50 - 95050 -950 This displays the exhaust oxygen sensor output voltage.
Should fluctuate constantly within a range between
10mV (lean exhaust) and 1000mV (rich exhaust) while
operating in closed loop.
19B1 Sho rt Te rm Fuel
Trim (Bank 1)%-6 - 0-6 - 0 The short term fuel trim to a bank represents a short term
co rrection to the ba nk fue l de liv e ry by the ECM in
response to the amount of time the bank fuel control
oxygen sensor voltage spends above or below the
450mV threshold. If the oxygen sensor voltage has
ma inly rema ine d less tha n 450mV, indicating a lea n a ir/
fue l, short te rm fuel trim will incre a se into the positiv e
range above 0% and the ECM will pass fuel. If the
oxygen sensor voltage stays mainly above the threshold,
short term fuel trim will decrease below 0% into the
negative range while the ECM reduces fuel delivery to
compensate for the indicated rich condition. Under
ce rtain co nditions such a s e xte nde d idle a nd high
ambient temperatures, canister purge may cause short
term fuel trim to rea d in the ne ga tiv e ra nge during no rma l
operation. Fuel trim values at maximum authority may
indica te an ex cessiv ely rich o r lea n sy stem.
20B1 Lo ng Term Fue l
Trim (Bank 1)%-10 - 0-5 - 0 The long te rm fue l trim is deliv ere d fro m the sho rt term
fuel term values and represents a long term correction of
fuel delivery for bank in question. A value of 0% indicates
that fuel delivery requires no compensation to maintain
the ECM commanded air fuel ratio. A negative value
indica tes tha t the fuel syste m is rich a nd fue l de live ry is
being reduced (decreased injector pulse width). A
positive value indicates that a lean condition exists and
the ECM is compensating by add fuel (increased injector
pulse width). Be ca use lo ng term fue l trim te nds to fo llow
short term fuel trim, a value in the negative range due to
canister purge at idle should not be considered unusual.
Fuel trim values at maximum authority may indicate an
excessively rich or lean system.
21Injection Pulse Widthms3.0 - 1.03.0 - 4.0 This displays the amount of time the ECM is
co mma nding e ach injecto r On during ea ch e ngine cycle.
A longer injector pulse width will cause more fuel to be
delivered. Injector pulse width should increase with
increased engine load.
22Power EnrichmentYe s / N oNoNo The ECM provides the extra amount of fuel when it
detects a rapid increase in the throttle position and air
flo w (Po wer Enrichment). Under this co ndition the ECM
should detect a “rich condition (high oxygen sensor
voltage).
23Decelera tion Fue l
Cut o ff Active /
InactiveInactiveIna ctiveThe ECM reduces the amount of fuel injected when it
detects a decrease in the throttle position and the air
flow. When deceleration is very fast, the ECM may cut off
fue l co mple te ly. Until e na ble co nditions me et the e ngine
rev olution less tha n 1000rpm o r MAP le ss tha n 10kPa .
24Time From Start--This displays the engine time elapsed since the engine
w as sta rte d. If the engine is stoppe d, engine run time will
be rese t to 00:00:00
Tech 2 ParameterUnitsIdle2000rpmDescription

6E–76 ENGINE DRIVEABILITY AND EMISSIONS
MISCELLANEOUS TEST
The state of each circuit can be tested by using
miscellaneous test menus. Especially when DTC
cannot be detected, a faulty circuit can be diagnosed by
testing each circuit by means of these menus.
Even DTC has been detected, the circuit tests using
these menus could help discriminate between a
mechanical trouble and an electrical trouble.
Connect Tech 2 and select “Powertrain”, “2.XL L4
HV240” & “Miscellaneous Test”.
F0: Lamps
F0: Malfunction Indicator Lamp
When the Tech 2 is operated, “Malfunction Indicator
Lamp (Check Engine Lamp)” is turned on or off.
The circuit is normal if the “Malfunction Indicator Lamp
(Check Engine Lamp)” in the instrument panel is turned
on or off in accordance with this operation.
F1: Relays
F0: Fuel Pump Relay
When the Tech 2 is operated, fuel pump relay signal
turns ON or OFF.
The circuit is normal if fuel pump sound is generated in
accordance with this operation when key switch is
turned ON.
F1: A /C Clutch Relay
When the Tech 2 is operated, A/C clutch relay signal
turns ON or OFF.
The circuit is normal if A/C compressor clutch is
energized in accordance with this operation when the
engine is running.
F2: EVAP
F0: Purge Solenoid
When the Tech 2 is operated, duty ratio of EVAP purge
solenoid is changed 10%-by-10%.
Press “Increase” key.
Then, EVAP Purge Solenoid is increases 10%-by-
10%.
Press “Quit” Key.F3: IAC System
F0: IA C Control
When the Tech 2 is operated, “Idle Air Control”
increases or decreases 5steps-by-5steps up to
150steps.
The circuit is normal if idle engine speed is changed in
accordance with this operation.
Press “Increase” key.
Then, Idle Air Control is increases 1osteps-by-
10steps up to 160steps. Engine speed is also
changed by this operation.
Press “Quit” Key.
F1: IA C Reset
When the Tech 2 is operated, “Idle Air Control” resets.
The circuit is normal if idle engine speed is droped in
accordance with this operation.
Press “Increase” key.
Then, Desired Idle speed is increases 50rpm-by-
50rpm up to 1550rpm. Engine speed is also changed
by this operation.
Press “Quit” Key. Purge Solenoid
Engine Speed 800 RPM
Desired Idle Speed 762 RPM
Engine Coolant Temperature 80 °C
Start Up ECT 50 °C
Intake Air Temperature 30 °C
Start Up IAT 25 °C
Manifold Absolute Pressure 35kPa
EVAP Purge Solenoid 30%
IAC Control
Engine Speed 800 RPM
Desired Idle Speed 762 RPM
Engine Coolant Temperature 80 °C
Start Up ECT 50 °C
Intake Air Temperature 30 °C
Start Up IAT25 °C
Manifold Absolute Pressure 35kPa
Idle Air Control 30 Steps
IAC Reset
Engine Speed 800 RPM
Desired Idle Speed 762 RPM
Engine Coolant Temperature 80 °C
Start Up ECT 50 °C
Intake Air Temperature 30 °C
Start Up IAT 25 °C
Manifold Absolute Pressure 35kPa
Idle Air Control 30 Steps

ENGINE DRIVEABILITY AND EMISSIONS 6E–81
SNAPSHOT DISPLAY WITH TIS2000
Procedures for transferring and displaying Tech2
snapshot data by using TIS2000 [Snapshot Upload]
function is described below.
Snapshot data can be displayed with [Snapshot Upload]
function included in TIS2000.
1. Record the snapshot data, in Tech2.
2. Transfer the snapshot data to PC.By analyzing these data in various methods, trouble
conditions can be checked.
Snapshot data is displayed by ex ecuting the three steps
below shown:
After recording the snapshot in Tech2, transfer the data
from Tech2 to PC by the below procedures.
1. Start TIS2000.
2. Select [Snapshot Upload] on the TIS2000 start
screen.
3. Select [Upload from trouble diagnosis tool (transfer
from diagnosis tester)] or click the corresponding
icon of the tool bar.
4. Select Tech2, and transfer the recorded snapshot
information. 5. Select the transferred snapshot.
6. After ending transfer of the snapshot, data
parameter list is displayed on the screen.

6E–82 ENGINE DRIVEABILITY AND EMISSIONS
3. Snapshot data is displayed with TIS2000
[Snapshot Upload] function.
Snapshot is stored in the PC hard disk or floppy disk,
and can be displayed any time.
Stored snapshot can be displayed by the below
procedures.
1. Start TIS2000.
2. Select [Snapshot Upload] on the TIS2000 start
screen.3. Select [Open the existing files] or click the
corresponding icon of the tool bar.
4. Select the transferred snapshot.
5. Open the snapshot, to display the data parameter
list on the screen.
Graph display Values and graphs (Max. 3 graphs):
1. Click the icon for graph display. [Graph Parameter]
window opens.
2. Click the first graph icon of the window upper part,
and select one parameter from the list of the window
lower part. Selected parameter is displayed nest to
the graph icon. Graph division can be selected in
the field on the parameter right side.
3. Repeat the same procedures with the 2nd and 3rd
icons.
4. After selecting all parameters to be displayed (Max .
3 parameters), click [OK] button.
5. Parameter selected is displayed in graph form on
the right of the data parameter on the screen. 6. Graph display can be moved with the navigation
icon.
7. For displaying another parameter by graph, click the
parameter of the list, drug the mouse to the display
screen while pressing the mouse button and release
the mouse button. New parameter is displayed at
the position of the previous parameter. For
displaying the graph display screen in full size,
move the cursor upward on the screen. When the
cursor is changed to the magnifying glass form, click
the screen. Graph screen is displayed on the whole
screen.

6E–118 ENGINE DRIVEABILITY AND EMISSIONSP1167 D Fuel Supply System Rich During
Deceleration Fuel Cutoff1. No DTC relating to MAP sensor, TPS,
EVAP purge, ECT sensor, CKP sensor,
VSS, injector control circuit and ignition
control circuit.
2. O
2 sensor bank 1 output voltage is more
than 550mV in deceleration fuel cutoff
mode.No fail-safe function. O
2 sensor output voltage is below 550mV. 1. Sensor harness open or short to ground
circuit.
2. O
2 sensor malfunction.
3. MAF sensor output is incorrect.
4. Air intake line malfunction.
5. IAC valve malfunction.
6. Low fuel pressure.
7. Injector malfunction.
8. EVAP purge solenoid valve malfunction.
9. Ignition system malfunction.
10. Spark plug malfunction.
11. ECM malfunction.J2-6/
J2-21
P1171 D Fuel Supply System Lean During Power
Enrichment 1. No DTC relating to MAP sensor, TPS,
EVAP purge, ECT sensor, CKP sensor,
VSS, injector control circuit and ignition
control circuit.
2. Engine coolant temperature is more than
60deg. C.
3. Mass air flow is below 13.5m/s.
4. O
2 sensor bank 1 output voltage is below
350mV in power enrichment mode. No fail-safe function. O
2 sensor output voltage is more than
350mV.1. Sensor harness open or short to ground
circuit.
2. O
2 sensor malfunction.
3. MAF sensor output is incorrect.
4. Air intake line malfunction.
5. IAC valve malfunction.
6. Low fuel pressure.
7. Injector malfunction.
8. ECM malfunction.J2-6/
J2-21
P1625 B ECM System Reset ECM reset has occurred other than “On”. Engine control disabled. Memory are is OK. 1. Electrical interference.
2. Magnetic interference.
3. ECM malfunction.-
P1626 - Immobilizer No Signal No response from immobilizer control unit. 1. Engine does not start.
2. Check engine lamp flash.No recovery. 1. ECM and immobilizer control unit
communication circuit open circuit, short to
ground circuit or short to voltage circuit.
2. ECM malfunction.
3. Immobilizer control unit malfunction.
4. Transponder key malfunction.J2-23/
J2-32
P1631 - Immobilizer Wrong Signal Received response is not correct.1. ECM malfunction.
2. Immobilizer control unit malfunction.
3. Transponder key malfunction.-
P1648 - Wrong Security Code Entered Received incorrect security code.1. ECM malfunction.
2. Immobilizer control unit malfunction.
3. Transponder key malfunction.-
P1649 - Immobilizer Function Not Programmed Immobilizer function is not programmed in the
ECM.ECM malfunction. -
P1693 B Tachometer Output Low Voltage Tacho output circuit short to ground circuit. No fail-safe function. Tacho output circuit is correct condition. 1. Tacho output circuit short to ground circuit.
2. Poor connector connection.
3. ECM malfunction.J2-25 Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM
Pin No.

ENGINE DRIVEABILITY AND EMISSIONS 6E–119
DIAGNOSTIC TROUBLE CODE (DTC) P0107 MANIFOLD ABSOLUTE
PRESSURE CIRCUIT LOW INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The manifold absolute pressure (MAP) sensor responds
to changes in intake manifold pressure. The MAP
sensor signal voltage to the engine control module
(ECM) varies from below 2 volts at idle (low manifold
pressure) to above 4 volts with the ignition ON, engine
not running or at wide-open throttle (high manifold
pressure).
A “speed density” method of determining engine load is
used on the 2.4L engine. This is calculated using inputs
from the MAP sensor, the CKP Sensor, and the IntakeAir Temperature (IAT) sensor. The MAP sensor is the
main sensor used in this calculation, and measuring
engine load is its main function.
The ECM monitors the MAP signals for voltages outside
the normal range (10-104 kPa) of the MAP sensor. If the
ECM detects a MAP signal voltage that is ex cessively
low, Diagnostic Trouble Code P0107 will be set.
Diagnostic Aids
Check for the following conditions:
 Poor connection at ECM - Inspect harness
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0107 A Manifo ld Absolute Pre ssure Circuit
Lo w Input1. No DTC re lating to TPS.
2. Throttle position is more than 0% if engine
spee d is be lo w 1000rpm, or throttle po si-
tio n mo re tha n 5% if engine spe ed is mo re
than 1000rpm.
3. MAP se nso r o utput is below 12kPa .The ECM uses default manifold absolute
pressure value based on engine speed
and thro ttle po sitio n.