2004 ISUZU TF SERIES section 1A

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
V
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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
C-124
V

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 -
C-124
C-57


4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–149
7 Repair the short to battery voltage circuit between the
ECM and vacuum pressure sensor.
Was the problem solved?
- Verify repair Go to Step 10
8 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 9Go to Step 10
9 Replace the vacuum pressure sensor assembly.
Is the action complete? - Verify repair -
10 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 11
11 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 -
C-124
C-57


4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–151
7 Using the DVM and check the vacuum pressure
sensor power supply circuit.
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 short to vacuum pessure
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 vacuum pressure sensor
ground.
Is the action complete? - Verify repair -
9 Repair the short to ground circuit between the vacuum
p r e s s u r e s e n s o r.
Was the problem solved? - Verify repair Go to Step 12
10 Substitute a known good MAF & IAT sensor assembly
a n d re ch e c k.
Was the problem solved? - Go to Step 11Go to Step 12
11 R e p l a c e t h e M A F & I A T s e n s o r a s s e m b l y .
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
1 3 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 -
C-124




6E –156 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
11 Using the DVM and check the IAT 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 & IAT 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 & IAT 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 14
12 Substitute a known good MAF & IAT sensor assembly and recheck.
Was the problem solved? —Go to Step 13 Go to Step 14
13 Replace the MAF & IAT sensor assembly. Is the action complete? —Verify repair —
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
15 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
C-11692Breaker Box



3
92
C-116
C-57(B)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –159
7 Using the DVM and check the IAT 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 short to sensor ground or 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 short to sensor ground or ground circuit.
Was the problem found?
— Repair faulty
harness and verify repair Go to Step 10
8 Substitute a known good MAF & IAT sensor assembly and recheck.
Was the problem solved? —Go to Step 9 Go to Step 10
9 Replace the MAF & IAT sensor assembly. Is the action complete? —Verify repair —
10 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 11
11 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
8492


Breaker Box


92
84
C-57(B)

6E–164 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
12 Substitute a known good ECT sensor assembly and
recheck.
Was the problem solved?—Go to Step 13Go to Step 14
13 Replace the ECT sensor.
Is the action complete?—Verify repair—
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
15 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