ISUZU TF SERIES 2004 Workshop Manual

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –139
8 Using the DVM and check the MAF sensor signal
circuit.
1. Ignition “On ”, engine “Off ”.
2. Disconnect the MAF sensor connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Less than 1V Go to Step 9 Repair faulty
harness and verify repair
9 Substitute a known good MAF & IAT sensor assembly and recheck.
Was the problem solved? —Go to Step 10 Go to Step 11
10 Replace the MAF & IAT sensor assembly. Is the action complete? —Verify repair —
11 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 12
12 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 —
Step Action Value(s) Yes No
5
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6E–140 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0105 (SYMPTOM CODE 1) (FLASH
CODE 34) VACUUM PRESSURE SENSOR CIRCUIT HIGH INPUT
DIAGNOSTIC TROUBLE CODE (DTC) P0105 (SYMPTOM CODE 2) (FLASH
CODE 34) VACUUM PRESSURE SENSOR CIRCUIT LOW INPUT
DIAGNOSTIC TROUBLE CODE (DTC) P0105 (SYMPTOM CODE 7) (FLASH
CODE 34) VACUUM PRESSURE SENSOR VOLTAGE SUPPLY CIRCUIT HIGH
INPUT
DIAGNOSTIC TROUBLE CODE (DTC) P0105 (SYMPTOM CODE 9) (FLASH
CODE 34) VACUUM PRESSURE SENSOR VOLTAGE SUPPLY CIRCUIT LOW
INPUT

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–141
Condition for setting the DTC and action taken when the DTC sets
Circuit description
The ECM monitors altitude from the barometric
pressure sensor. To apply specified vacuum pressure to
the turbocharger wastegate valve, ECM sends control
signal to the wastegate control solenoid depending on
altitude.
Then, apply vacuum pressure to the turbocharger
wastegate valve is monitored by the ECM form the
vacuum pressure sensor output signal. The ECM
controls wastegate control solenoid based on signal
from vacuum pressure sensor output.
The output voltage ex cessively high or low, DTC P0105
(Symptom Code 1) or P0105 (Symptom Code 2) will be
stored.
The supply voltage is out of range, DTC P0105
(Symptom Code 7) or P0105 (Symptom Code 9) will be
stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the DTC P0105 display on the Tech 2 while moving
connectors and wiring harnesses. A change in the
display will indicate the location of the fault.
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
34 P0105 1 ON Vacuum Pressure Sensor
Circuit High InputVacuum sensor output
voltage is more than 4.4V.1. Fuel injection quantity is
r e d u c e d .
2. ECM use 615hpa
conditio ns for
turbo cha rge r wa ste gate
contro l. 2 ON Vacuum Pressure Sensor
Circuit Low InputVacuum sensor output
voltage is below 0.5V.
7 ON Vacuum Pressure Sensor
Volta ge Supply Circuit High
InputVacuum senso r po wer supply
voltage is more than 5.2V.1. Fuel injection quantity is
r e d u c e d .
2. ECM use vacuum sensor
output voltage 5.0V
condition as substitute. 9 ON Vacuum Pressure Sensor
Volta ge Supply Circuit Lo w
InputVacuum senso r po wer supply
voltage is below 4.5V.

6E–142 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0105 (Symptom Code 1) (Flash Code 34)
Vacuum Pressure Sensor Circuit High Input
Step Action Value(s) Yes No
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
-Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1 . 1 C o n n e c t t h e Te c h 2 .
2. Review and record the failure information.
3. Select "F0: Read DTC Infor As Stored By ECU" in
"F0: Diagnostic Trouble Codes".
Is the DTC P0105 (Symptom Code 1) stored as
"Present Failure"? - Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition "On" and engine "Off".
2. Select "F1: Clear DTC Information" in "F0:
Diagnostic Trouble Codes" with the Tech 2 and
c l e a r t h e D T C i n f o r m a t i o n .
3. Operate the vehicle and monitor the "F0: Read
DTC Infor As Stored By ECU" in the "F0:
Diagnostic Trouble Codes".
Was the DTC P0105 (Symptom Code 1) stored in this
ignition cycle? - Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the vacuum
pressure sensor or ECM connector. If a poor/faulty
connection is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 5
5 V i s u a l l y c h e c k t h e v a c u u m s e n s o r.
Was the problem found? - Go to Step 9Go to Step 6
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–143
6 Using the DVM and check the vacuum pressure
sensor ground circuit.
Breaker box is available:
1. Ignition "Off", engine "Off".
2. Install the breaker box as type A. (ECM
disconnected) Ref. Page 6E-103
3. Disconnect the vacuum pressure sensor
connector.
4. Check the circuit for open circuit.
Was the problem found?
Breaker box is not available:
1 . I g n i t i o n " O f f " , e n g i n e " O f f " .
2. Disconnect the vacuum pressure sensor
connector and ECM connector.
3. Check the circuit for open circuit.
Was the problem found?
-Repair faulty
harness and
verify repair Go to Step 7
7 Using the DVM and check the vacuum pressure
sensor ground circuit.
1 . I g n i t i o n " O n " , e n g i n e " O f f " .
2. Disconnect the vacuum pressure sensor
connector.
3 . C h e c k t h e c i r c u i t f o r s h o r t t o p o w e r s u p p l y c i r c u i t .
Was the DVM indicated specified value?
Less than 1V Go to Step 8Repair faulty
harness and
verify repair Step Action Value(s) Yes No
93
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6E–144 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
8 Using the DVM and check the vacuum pressure
sensor signal circuit.
1 . I g n i t i o n " O n " , e n g i n e " O f f " .
2. Disconnect the vacuum pressure sensor
connector.
3 . C h e c k t h e c i r c u i t f o r s h o r t t o p o w e r s u p p l y c i r c u i t .
Was the DVM indicated specified value?
Less than 1V Go to Step 9Repair faulty
harness and
verify repair
9 Substitute a known good vacuum pressure sensor
a n d re ch e c k.
Was the problem solved? - Go to Step 10Go to Step 11
10 Replace the vacuum pressure sensor.
Is the action complete? - Verify repair -
11 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 12
1 2 R e p l a c e t h e E C M .
I s t h e a c t i o n c o mp l e t e ?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual.
Following ECM programming, the immobiliser 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 - Step Action Value(s) Yes No
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–145
Diagnostic Trouble Code (DTC) P0105 (Symptom Code 2) (Flash Code 34)
Vacuum Pressure Sensor Circuit Low Input
Step Action Value(s) Yes No
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
-Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select "F0: Read DTC Infor As Stored By ECU" in
"F0: Diagnostic Trouble Codes".
Is the DTC P0105 (Symptom Code 2) stored as
"Present Failure"? - Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition "On" and engine "Off".
2. Select "F1: Clear DTC Information" in "F0:
Diagnostic Trouble Codes" with the Tech 2 and
c l e a r t h e D T C i n f o r m a t i o n .
3. Operate the vehicle and monitor the "F0: Read
DTC Infor As Stored By ECU" in the "F0:
Diagnostic Trouble Codes".
Was the DTC P0105 (Symptom Code 2) stored in this
ignition cycle? - Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the vacuum
pressure sensor or ECM connector. If a poor/faulty
connection is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 5
5 V i s u a l l y c h e c k t h e v a c u u m p r e s s u r e s e n s o r .
Was the problem found? - Go to Step 9Go to Step 6
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6E–146 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
6 Using the DVM and check the vacuum pressure
sensor signal circuit.
Breaker box is available:
1 . I g n i t i o n " O f f " , e n g i n e " O f f " .
2. Install the breaker box as type A. (ECM
disconnected) Ref. Page 6E-103
3. Disconnect the vacuum pressure sensor
connector.
4. Check the circuit for open, short to sensor ground
or short to ground circuit.
Was the problem found?
Breaker box is not available:
1 . I g n i t i o n " O f f " , e n g i n e " O f f " .
2. Disconnect the vacuum pressure sensor
connector and ECM connector.
3. Check the circuit for open, short to sensor ground
or short to ground circuit.
Was the problem found?
-Repair faulty
harness and
verify repair Go to Step 7
7 Using the DVM and check the vacuum pressure
sensor power supply circuit.
1. Ignition "On", engine "Off".
2. Disconnect the vacuum pressure sensor
connector.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
Approx imately
5.0V
Go to Step 9Go to Step 8
85
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–147
8 Repair the open circuit between the ECM and vacuum
p r e s s u r e s e n s o r.
Was the problem solved?
- Verify repair Go to Step 11
9 Substitute a known good vacuum pressure sensor
a s s e m b l y a n d r e c h e c k .
Was the problem solved? - Go to Step 10Go to Step 11
1 0 R e p l a c e t h e v a c u u m s e n s o r a s s e m b l y .
Is the action complete? - Verify repair -
11 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 12
1 2 R e p l a c e t h e E C M .
I s t h e a c t i o n c o mp l e t e ?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual.
Following ECM programming, the immobiliser 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 -
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6E–148 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0105 (Symptom Code 7) (Flash Code 34)
Vacuum Pressure Sensor Voltage Supply Circuit High Input
Step Action Value(s) Yes No
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
-Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select "F0: Read DTC Infor As Stored By ECU" in
"F0: Diagnostic Trouble Codes".
Is the DTC P0105 (Symptom Code 7) stored as
"Present Failure"? - Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition "On" and engine "Off".
2. Select "F1: Clear DTC Information" in "F0:
Diagnostic Trouble Codes" with the Tech 2 and
c l e a r t h e D T C i n f o r m a t i o n .
3. Operate the vehicle and monitor the "F0: Read
DTC Infor As Stored By ECU" in the "F0:
Diagnostic Trouble Codes".
Was the DTC P0105 (Symptom Code 7) stored in this
ignition cycle? - Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the vacuum
pressure sensor or ECM connector. If a poor/faulty
connection is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 5
5 V i s u a l l y c h e c k t h e v a c u u m p r e s s u r e s e n s o r .
Was the problem found? - Go to Step 8Go to Step 6
6 Using the DVM and check the vacuum pressure
sensor power supply circuit.
1. Ignition "On", engine "Off".
2. Disconnect the vacuum pressure sensor
connector.
3. Check the circuit for short to battery voltage
circuit.
Was the DVM indicated specified value?
Approx imately
5.0V
Go to Step 8Go to Step 7
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