ISUZU TF SERIES 2004 Workshop Manual

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–129
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The mass air flow (MAF) sensor is part of the intake air
system. It is fitted between the air cleaner and
turbocharger and measure the mass air flowing into the
engine.
The mass air flow (MAF) sensor element measures the
partial air mass through a measurement duct on the
sensor housing.
The ECM monitors the MAF sensor supply voltage and
MAF sensor output voltage. The supply voltage is out of
range, DTC P0100 (Symptom Code 7) or P0100
(Symptom Code 9) will be stored. The output voltage
ex cessively high or low, DTC P0100 (Symptom Code B)
or P0100 (Symptom Code C) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
 Poor connections.
 Misrouted harness.
 Rubbed through wire insulation.
 Broken wire inside the 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 “Mass Air Flow” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.
Diagnostic Trouble Code (DTC) P0100 (Symptom Code 7) (Flash Code 65)
Mass Air Flow (MAF) Sensor Voltage Supply Circuit High Input
Flash
CodeCodeSymptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
65 P0100 7 ON Ma ss Air Flo w (MAF) Senso r
Voltage Supply Circuit High
InputMAF sensor power supply
voltage is more than 5.2V.ECM uses ma ss a ir flo w
1600mg/strk & EGR 10% co n-
ditions as substitute.
9 ON Mass Air Flow (MAF) Sensor
Voltage Supply Circuit Low
InputMAF sensor power supply
voltage is below 4.6V.
B ON Mass Air Flow (MAF) Sensor
Output Circuit Low Input1. Engine speed is between
600rpm and 5000rpm.
2. MAF se nsor o utput is
below -33.7mg/strk.
C ON Mass Air Flow (MAF) Sensor
Output Circuit High Input1. Engine speed is between
600rpm and 5000rpm.
2. MAF sensor output is more
tha n 1378mg/strk (4JA1-TC)
o r 1784mg/strk (4JH1-TC).
Step Action Value(s) Yes No
1Was 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 P0100 (Symptom Code 7) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3

6E –130 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
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
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU ” in the “F0:
Diagnostic Trouble Codes ”.
Was the DTC P0100 (Symptom Code 7) stored in this
ignition cycle? —Go to Step 4 Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the MAF 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 Visually check the MAF sensor. Was the problem found? —Go to Step 11 Go to Step 6
6 Using the DVM and check the MAF sensor power supply circuit.
1. Ignition “On ”, engine “Off ”.
2. Disconnect the MAF & IAT 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 11 Less than 1V:
Go to Step 7
More than
specified value: Go to Step 8
7 Repair the open circuit between the ECM and MAF sensor.
Was the problem solved?
— Verify repair Go to Step 8
Step Action Value(s) Yes No
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –131
8 Using the DVM and check the MAF sensor power
supply circuit.
1. Ignition “Off ”, engine “Off ”.
2. Disconnect the MAF & IAT sensor connector and ECM connector.
3. Check the circuit for short to MAF sensor +12V supply circuit.
Was the DVM indicated specified value?
No continuity Go to Step 10Go to Step 9
9 Repair the circuit for short to MAF sensor +12V supply circuit.
Is the action complete? —Verify repair —
10 Repair the short to battery voltage circuit between the ECM and MAF sensor.
Was the problem solved?
— Verify repair Go to Step 13
11 Substitute a known good MAF & IAT sensor assembly and recheck.
Was the problem solved? —Go to Step 12 Go to Step 13
12 Replace the MAF & IAT sensor assembly. Is the action complete? —Verify repair —
13 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 14
14 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
4
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6E –132 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0100 (Symptom Code 9) (Flash Code 65)
Mass Air Flow (MAF) Sensor Voltage Supply Circuit Low Input
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check ”
performed?
— Go to Step 2 Go 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 P0100 (Symptom Code 9) stored as
“ Present Failure ”? —Go to Step 3 Refer 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
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU ” in the “F0:
Diagnostic Trouble Codes ”.
Was the DTC P0100 (Symptom Code 9) stored in this
ignition cycle? —Go to Step 4 Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the MAF 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 Visually check the MAF sensor. Was the problem found? —Go to Step 10 Go to Step 6
6 Using the DVM and check the MAF sensor power supply circuit.
1. Ignition “On ”, engine “Off ”.
2. Disconnect the MAF & IAT sensor connector.
3. Check the circuit for short to ground circuit.
Was the DVM indicated specified value?
Approx imately 5.0V Go to Step 10Go to Step 7
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –133
7 Using the DVM and check the MAF sensor power
supply circuit.
1. Ignition “Off ”, engine “Off ”.
2. Disconnect the MAF & IAT sensor connector and ECM connector.
3. Check the circuit for short to MAF sensor ground circuit.
Was the DVM indicated specified value?
No continuity Go to Step 9Go to Step 8
8 Repair the circuit for short to MAF sensor ground. Is the action complete? —Verify repair —
9 Repair the short to ground circuit between the ECM and MAF sensor.
Was the problem solved?
— Verify repair Go to Step 12
10 Substitute a known good MAF & IAT sensor assembly and recheck.
Was the problem solved? —Go to Step 11 Go to Step 12
11 Replace the MAF & IAT sensor assembly. Is the action complete? —Verify repair —
12 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 13
13 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
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6E –134 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0100 (Symptom Code B) (Flash Code 65)
Mass Air Flow (MAF) Sensor Output Circuit Low Input
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check ”
performed?
— Go to Step 2 Go 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 P0100 (Symptom Code B) stored as
“ Present Failure ”? —Go to Step 3 Refer 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
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU ” in the “F0:
Diagnostic Trouble Codes ”.
Was the DTC P0100 (Symptom Code B) stored in this
ignition cycle? —Go to Step 4 Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the MAF 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 Visually check the MAF sensor. Was the problem found? —Go to Step 11 Go to Step 6
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –135
6 Using the DVM and check the MAF sensor signal
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 MAF & IAT 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. Ignition “Off ”, engine “Off ”.
2. Disconnect the MAF & IAT 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 MAF sensor power supply circuit.
1. Ignition “On ”, engine “Off ”.
2. Disconnect the MAF & IAT 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
Step Action Value(s) Yes No
C-11688Breaker Box




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6E –136 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
8 Repair the open circuit between the ECM and MAF
sensor.
Was the problem solved?
— Verify repair Go to Step 13
9 Using the DVM and check the MAF sensor +12V supply circuit.
1. Ignition “On ”, engine “Off ”.
2. Disconnect the MAF & IAT sensor connector.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
10-14.5V Go to Step 11Go to Step 10
10 Repair the open circuit between the ECM main relay and MAF sensor.
Was the problem solved? —Verify repair Go to Step 11
11 Substitute a known good MAF & IAT sensor assembly and recheck.
Was the problem solved? —Go to Step 12 Go to Step 13
12 Replace the MAF & IAT sensor assembly. Is the action complete? —Verify repair —
13 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 14
14 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
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –137
Diagnostic Trouble Code (DTC) P0100 (Symptom Code C) (Flash Code 65)
Mass Air Flow (MAF) Sensor Output Circuit High Input
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check ”
performed?
— Go to Step 2 Go 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 P0100 (Symptom Code C) stored as
“ Present Failure ”? —Go to Step 3 Refer 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
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU ” in the “F0:
Diagnostic Trouble Codes ”.
Was the DTC P0100 (Symptom Code C) stored in this
ignition cycle? —Go to Step 4 Refer to
Diagnostic Aids and Go to Step
4
4 Check for poor/faulty connection at the MAF 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 Visually check the MAF sensor. Was the problem found? —Go to Step 11 Go to Step 6
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6E –138 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
6 Using the DVM and check the MAF 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 MAF sensor connector.
4. Check the circuit for open circuit.
Was the problem found?
Breaker box is not available:
1. Ignition “Off ”, engine “Off ”.
2. Disconnect the MAF 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 MAF sensor ground 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 8 Repair faulty
harness and verify repair
Step Action Value(s) Yes No
C-11692Breaker Box



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