2004 ISUZU TF SERIES Workshop Manual

winter tyres maintenance schedule brakes air filter tailgate warning

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ISUZU TF SERIES 2004 Workshop Manual ENGINE DRIVEABILITY AND EMISSIONS 6E–73
20 A/C Reque st Ye s/NoOffOff This displays the air conditioner request signal. This
should display “On” whe n the air conditio ne r switch is
switche d

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ISUZU TF SERIES 2004 Workshop Manual 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) w

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.

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ISUZU TF SERIES 2004 Workshop Manual 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

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

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ISUZU TF SERIES 2004 Workshop Manual 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

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

Page 2653 of 4264

ISUZU TF SERIES 2004 Workshop Manual ENGINE DRIVEABILITY AND EMISSIONS 6E–77
F4: Injector Balance Test
When the Tech 2 is operated, selected injector turns ON
or OFF.
The circuit is normal if engine vibration is changed at
selected cyl

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ISUZU TF SERIES 2004 Workshop Manual 6E–78 ENGINE DRIVEABILITY AND EMISSIONS
PLOTTING SNAPSHOT GRAPH
This test selects several necessary items from the data
list to plot graphs and makes data comparison on a long
term basis. It is an e

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ISUZU TF SERIES 2004 Workshop Manual ENGINE DRIVEABILITY AND EMISSIONS 6E–79
Plotting Graph Flow Chart (Plotting graph after obtaining vehicle information)
D0 6RY 0 0167

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ISUZU TF SERIES 2004 Workshop Manual 6E–80 ENGINE DRIVEABILITY AND EMISSIONS
Flow Chart for Snapshot Replay (Plotting Graph)
0 60RX0 -40

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