2004 ISUZU TF SERIES Workshop Manual

transmission fluid hood release ECU bluetooth steering steering wheel

Page 2209 of 4264

ISUZU TF SERIES 2004 Workshop Manual 3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-213
Diagnostic Trouble Code (DTC) P0171 (Flash Code 44) O2 Sensor System
Too Lean (Bank 1)
Diagnostic Trouble Code (DTC) P0174 (Flash Code 44) O2 Sensor S

Page 2210 of 4264

ISUZU TF SERIES 2004 Workshop Manual 6E-214 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
6
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.

6E-214 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
6
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position"
from 0% to 100% depending on accelerator pedal
operation?
- Go to Step 8 Go to Step 7
7
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the TPS within 0% to 100%.
Was the action complete?
- Verify repair -
8
Check for the following conditions.
Objects blocking the throttle valve.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P0121 and Go to
Step 9
9
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"IAC Control" in the "IAC System".
3. Operate the Tech 2 in accrodance with procedure.
Was the engine speed changed, when the IAC Valve
is operating step by step?
- Go to Step 11 Go to Step 10
10
Check for the following conditions.
Objects blocking the IAC Valve.
Objects blocking the throttle valve.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P1508/P1509
and Go to Step
11
11
Check for injector for the affected bank.
Refer to 6E-106 "Injector Coil Test & Injector Balance
Test Procedure".
Was the injector operation correct?
- Go to Step 12 Refer to Injector
Coil Test &
Injector Balance
Test Procedure
12
Check for fuel pressure.
Refer to 6E-116 "Fuel System Diagnosis".
Was the fuel pressure correct?
- Go to Step 13 Refer to Fuel
System
Diagnosis
13
Replace the O2 sensor for the affected bank.
Was the problem solved?
- Verify repair Go to Step 14
14
Is the ECM programmed with the latest software
release?
If not, download the latest software to the ECM using
the "SPS (Service Programming System)".
Was the problem solved?
- Verify repair Go to Step 15

Page 2211 of 4264

ISUZU TF SERIES 2004 Workshop Manual 3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-215
Step Action Value (s) Yes No
15
Replace the ECM.
Is the action complete?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of

Page 2212 of 4264

ISUZU TF SERIES 2004 Workshop Manual 6E-216 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0172 (FLASH CODE 45) O2 SENSOR
SYSTEM TOO RICH (BANK 1)
DIAGNOSTIC TROUBLE CODE (DTC) P0175 (FLASH CODE 44) O2 SENSOR
S

Page 2213 of 4264

ISUZU TF SERIES 2004 Workshop Manual 3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-217
Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0172 B

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-217
Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0172 B O2 Sensor System Too
Rich (Bank 1) 45
P0175 B O2 Sensor System Too
Rich (Bank 2) 1. No DTC relating to MAF sensor, IAT sensor, ECT sensor,
TPS, CMP sensor, CKP sensor, VSS, injector control
circuit, ignition control circuit, O2 sensor circuit low voltage
& high voltage (bank 1 & 2) and O2 sensor circuit no
activity (bank 1 & 2).
2. Engine speed is more than 600rpm.
3. Intake air temperature is more than 50C.
4. Engine coolant temperature is between 35C and 120C.
5. Engine load is more than 20%.
6. EVAP purge solenoid valve on-duty is below 100%.
7. Air-fuel ratio correction volume is below 50% for 20
seconds. No fail-safe function.

CIRCUIT DESCRIPTION
To provide the best possible combination of driveability,
fuel economy, and emission control, a “closed loop"
air/fuel metering system is used. While in “closed loop,"
the Engine Control Module (ECM) monitors the heated
oxygen sensors (HO2S) signals and adjusts fuel
delivery based upon the HO2S signal voltages.
A
change made to fuel delivery will be indicated by the
long and short term fuel trim values which can be
monitored with a Tech 2. Ideal fuel trim values are
around 0%; if the HO2S signals are indicating a lean
condition the ECM will add fuel, resulting in fuel trim
values above 0%. If a rich condition is detected, the fuel
trim values will be below 0%, indicating that the ECM is
reducing the amount of fuel delivered. If an excessively
rich condition is detected on Bank 1, the ECM will se
t
DTC P0172 or P0175.
The ECM's maximum authority to control long term fuel
trim allows a range between –15% (automatic
transmission) or –12 (manual transmission) and +20%.
The ECM's maximum authority to control short term fuel
trim allows a range between –11% and +20%. The ECM
monitors fuel trim under various engine speed/load fuel
trim cells before determining the status of the fuel trim
diagnostic.

DIAGNOSTIC AIDS
Check for the following conditions:
Poor connection at ECM – Inspect harness
connectors for backed-out terminals, imprope
r
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
Damaged harness –Inspect the wiring harness fo
r
damage. If the harness appears to be OK, observe
the HO2S display on the Tech 2 while moving
connectors and wiring harnesses related to the
engine harness. A change in the display will indicate
the location of the fault.

Page 2214 of 4264

ISUZU TF SERIES 2004 Workshop Manual 6E-218 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0172 (Flash Code 45) O2 Sensor System Too
Rich (Bank 1)
Diagnostic Trouble Code (DTC) P0175 (Flash Code 44) O2 Sensor Sy

Page 2215 of 4264

ISUZU TF SERIES 2004 Workshop Manual 3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-219
Step Action Value (s) Yes No
6
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-219
Step Action Value (s) Yes No
6
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
Does the Tech 2 indicate correct "Throttle Position"
from 0% to 100% depending on accelerator pedal
operation?
- Go to Step 8 Go to Step 7
7
1. Using the Tech 2, ignition "On" and engine "Off".
2. Monitor the "Throttle Position" in the data display.
3. Adjust the TPS within 0% to 100%.
Is the action complete?
- Verify repair -
8
Check for the following conditions.
Objects blocking the throttle valve.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P0121 and Go to
Step 9
9
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"IAC Control" in the "IAC System".
3. Operate the Tech 2 in accrodance with procedure.
Was the engine speed changed, when the IAC Valve
is operating step by step?
-
Go to Step 11
Go to Step 10
10
Check for the following conditions.
Objects blocking the IAC Valve.
Objects blocking the throttle valve.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P1508/P1509
and Go to Step
11
11
Check for injector for the affected bank.
Refer to 6E-106 "Injector Coil Test & Injector Balance
Test Procedure".
Was the injector operation correct?
- Go to Step 12 Refer to Injector
Coil Test &
Injector Balance
Test Procedure
12
Check for fuel pressure.
Refer to 6E-116 "Fuel System Diagnosis".
Was the fuel pressure correct?
- Go to Step 13 Refer to Fuel
System
Diagnosis
13
Replace the O2 sensor for the affected bank.
Was the problem solved?
- Verify repair Go to Step 14
14
Is the ECM programmed with the latest software
release?
If not, download the latest software to the ECM using
the "SPS (Service Programming System)".
Was the problem solved?
- Verify repair Go to Step 15

Page 2216 of 4264

ISUZU TF SERIES 2004 Workshop Manual 6E-220 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
15
Replace the ECM.
Is the action complete?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of

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