2004 ISUZU TF SERIES fuel pressure

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-199
Step Action Value (s) Yes No
9
1. Using the Tech 2, ignition "On" and engine "On".
2. Monitor the "Mass Air Flow" in the data display.
Does the Tech 2 indicate correct "Mass Air Flow" as
shown in the following graph, when engine speed is
increasing little by little?
Characteris tic of MAF Sens or -Ref erence (No Engine Load)-
0 5 10 15 20 25 30 35 40 45 50
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Eng i ne Speed ( r pm) ( T ech2 R eadi ng )
Mass Air Flow (g/s)
( T ec h2 R eadi ng)
- Go to Step 11 Go to Step 10
10
Remove the MAF & IAT sensor assembly and check
for the following conditions.

Objects blocking the air cleaner.

Objects blocking the MAF sensor.

Objects blocking the throttle valve.

Vacuum leaking at intake duct.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Refer to DTC
P0101 and Go to
Step 11
11
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 13 Go to Step 12
12
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
13
13
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 14 Refer to Injector
Coil Test &
Injecotr Balance
Test Procedure
14
Check for fuel pressure.
Refer to 6E-116 "Fuel System Diagnosis".
Was the fuel pressure correct?
- Go to Step 15 Refer to Fuel
System
Diagnosis
15
Replace the O2 sensor for the affected bank.
Was the problem solved?
- Verify repair Go to Step 16

6E-202 3.5L ENGINE DRIVEABILITY AND EMISSIONS
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)
P0132 A O2 Sensor Circuit High
Voltage (Bank 1
Sensor 1) 15
P0152 A O2 Sensor Circuit High
Voltage (Bank 2
Sensor 1) 1. No DTC relating to ECT sensor, CMP sensor, CKP sensor,
VSS, injector control circuit, ignition control circuit and O2
sensor circuit no activity (bank 1 & 2).
2. Engine speed is between 1000rpm and 4000rpm.
3. Engine coolant temperature is between 70
and 110
.
4. Vehicle speed is between 0km/h and 120km/h.
5. Engine load is between 80% and 160%.
6. Throttle position fluctuation is below 0.28V.
7. O2 sensor bank 1 or bank 2 output voltage is below
600mV for 50 seconds. "Open Loop" fuel control.

CIRCUIT DESCRIPTION
The Engine Control Module (ECM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits. The
ECM constantly monitors the HO2S signal during
“closed loop" operation and compensates for a rich o
r
lean condition by decreasing or increasing injector pulse
width as necessary. If the HO2S voltage remains
excessively high for an extended period of time, DTC
P0132 or P0152 will be set.
DIAGNOSTIC AIDS
Check the following items:
 Fuel pressure – The system will go rich if pressure is
too high. The ECM can compensate for some
increase. However, if fuel pressure is too high, a DTC
P0132 or P0152 may be set. Refer to 6E-116 Fue
l
System Diagnosis.
 Perform “Injector Balance Test" – Refer to 6E-116
Fuel System Diagnosis.
 Check the canister for fuel saturation – If full of fuel,
check canister control and hoses.
 MAF sensor –The system can go rich if MAF senso
r
signal indicates an engine airflow measurement that
is not correct. Disconnect the MAF sensor to see it
the rich condition is corrected. If so, replace the MAF
sensor.

 Check for a leak in the fuel pressure regulato
r
diaphragm by checking the vacuum line to the
regulator for the presence of fuel. There should be no
fuel in the vacuum line.

An intermittent throttle position sensor output will
cause the system to go rich due to a false indication
of the engine accelerating.
 Shorted Heated Oxygen Sensor (HO2S) –If the
HO2S is internally shorted, the HO2S voltage
displayed on the Tech 2 will be over 1 volt. Try
disconnecting the affected HO2S with the key “ON,"
engine “OFF." If the displayed HO2S voltage
changes from over 1000 mV to around 450 mV,
replace the HO2S. Silicon contamination of the
HO2S can also cause a high HO2S voltage to be
indicated. This condition is indicated by a powdery
white deposit on the portion of the HO2S exposed to
the exhaust stream. If contamination is noticed,
replace the affected HO2S.
 Open HO2S Signal Circuit or Faulty HO2S–
A poor
connection or open in the HO2S signal circuit can
cause the DTC to set during deceleration fuel mode.
An HO2S which is faulty and not allowing a full
voltage swing between the rich and lean thresholds
can also cause this condition. Operate the vehicle by
monitoring the HO2S voltage with a Tech 2. If the
HO2S voltage is limited within a range between 300
mV to 600 mV, check the HO2S signal circuit wiring
and associated terminal conditions.
 If none of the above conditions are present, replace
the affected HO2S.

6E-206 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
11
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 13 Go to Step 12
12
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
13
13
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 14 Refer to Injector
Coil Test &
Injector Balance
Test Procedure
14
Check for fuel pressure.
Refer to 6E-116 "Fuel System Diagnosis".
Was the fuel pressure correct?
- Go to Step 15 Refer to Fuel
System
Diagnosis
15
Replace the O2 sensor for the affected bank.
Was the problem solved?
- Verify repair Go to Step 16
16
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 17
17
Replace the ECM.
Is the action complete?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. Following
ECM programming, the immobilizer system (if
equipped) must be linked to the ECM. Refer to section
11 “Immobilizer System-ECM replacement” for the
ECM/Immobilizer linking procedure.
- Verify repair -

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

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

6E-224 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%.
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 10
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

6E-332 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
8
1. Using a Tech 2, display the IAC value.
2. Check for a faulty, plugged, or sticking IAC
operation.
Was the problem found?
- Verify repair Go to Step 9
9
Check the CKP sensor signal or installation condition.
Refer to DTC P0336 "Crankshaft Position Sensor
Circuit Range/Performance" and DTC P0337
"Crankshaft Position Sensor Circuit No Signal".
Was a problem found?
- Verify repair Go to Step 10
10
Check for proper ignition voltage output with the spark
tester.
Was a problem found?
- Verify repair Go to Step 11
11
1. Remove the spark plugs and check for gas or oil
fouling cracks, wear, improper gap, burned
electrodes, heavy deposits, or improper heat
range.
2. If spark plugs are fouled, the cause of fouling must
be determined before replacing the spark plugs.
Was a problem found?
- Verify repair Go to Step 12
12
Check the fuel pressure. Refer to Fuel System
Diagnosis.
Was a problem found?
- Verify repair Go to Step 13
13
Perform the procedure in Fuel System Pressure Test
to determine if there is a problem with fuel delivery.
Was a problem found?
- Verify repair Go to Step 14
14
Visually/physically check the vacuum hose for splits,
kinks and proper connections and routing.
Was a problem found?
- Verify repair Go to Step 15
15
Check the exhaust system for a possible restriction:

Damaged or collapsed pipes.

Internal muffler failure.
Was a problem found?
- Verify repair Go to Step 16
16
Check for the following engine mechanical problems
(refer to Engine Mechanical section):

Low compression.

Leaking cylinder head gaskets.

Worn camshaft.

Camshaft drive belt slipped or stripped.
Was a problem found?
- Verify repair Go to Step 17

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-335
Step Action Value (s) Yes No
10
1. Remove the spark plugs and check for gas or oil
fouling cracks, wear, improper gap, burned
electrodes, heavy deposits, or improper heat
range.
2. If spark plugs are fouled, the cause of fouling must
be determined before replacing the spark plugs.
Was a problem found?
- Verify repair Go to Step 11
11
Check for water or alcohol contaminated fuel.
Was a problem found?
- Verify repair Go to Step 12
12
Perform the procedure in Fuel System Pressure Test
to determine if there is a problem with fuel delivery.
Refer to 6E-116 page.
Was a problem found?
- Verify repair Go to Step 13
13
1. Check the injector connectors.
2. If any of the connectors are connected at an
improper cylinder, connect as necessary.
Was a problem found?
- Verify repair Go to Step 14
14
Check for the following engine mechanical problems
(refer to Engine Mechanical section):

Low compression.

Leaking cylinder head gaskets.

Worn camshaft.

Camshaft drive belt slipped or stripped.
Was a problem found?
- Verify repair Go to Step 15
15
1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no
malfunctions have been found, review/inspect the
following:

Visual/physical inspection.

Tech 2 data.

All electrical connections within a suspected circuit
and/or system.
Was a problem found?
- Verify repair Go to Step 16
16
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 17