2004 ISUZU TF SERIES check engine

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-151
Step Action Value (s) Yes No
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?


 E-61(B)
E-63






- Verify repair Go to Step 5
5
Remove the MAF & IAT sensor assembly and visually
check.
Was the problem found?
- Go to Step 8 Go to Step 6
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).
Refer to 6E-99 page.
3. Disconnect the MAF sensor connector.
4. Check the circuit for open, short to sensor ground
or short to ground circuit.
Was the problem found?
B20B39




Breaker Box

E-63

6E-152 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No

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, short to sensor ground
or short to ground circuit.
Was the problem found?
E-61(B)




E-63





- Repair faulty
harness and
verify repair Go to Step 7
7
Using the DVM and check the MAF sensor power
supply circuit.
1. Ignition "Off", engine "Off".
2. Disconnect the MAF sensor connector and ECM
main relay.
3. Check the circuit for open circuit.
Was the problem found?


X-13E-63





-
Repair faulty
harness and
verify repair
Go to Step 8
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

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-155
CIRCUIT DESCRIPTION
The mass air flow (MAF) sensor measures the amount
of air which passes through it into the engine during a
given time. The Engine Control Module (ECM) uses the
mass air flow information to monitor engine operating
conditions for fuel delivery calculations. A large quantity
of air entering the engine indicates an acceleration o
r
high load situation, while a small quantity of air indicates
deceleration or idle.
The MAF sensor produces a frequency signal which
can be monitored using a Tech 2. The frequency will
vary within a range of around 5

8 g/s at idle to around
25 to 40 g/s at maximum engine load. DTC P0103 will
be set if the signal from the MAF sensor is above the
possible range of a normally operating MAF sensor.

DIAGNOSTIC AIDS
If DTC P0103 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.


Diagnostic Trouble Code (DTC) P0103 (Flash Code 61)
Mass Air Flow Sensor Circuit High Input
Step Action Value (s) Yes No
1
Was 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 By Priority" in "F0:
Diagnostic Trouble Code".
Is the DTC P0103 stored as "Present Failure"?
- Go to Step 3 Refer to
Diagnostic Aids
and Go to Step 3
3
1. Using the Tech2, ignition "On" and engine "Off".
2. Select "Clear DTC Information" with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the "F5: Failed
This Ignition" in "F2: DTC Information"
Was the DTC P0103 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?


 E-61(B)
E-63






- Verify repair Go to Step 5

6E-156 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
5
Remove the MAF & IAT sensor assembly and visually
check.
Was the problem found?
- Go to Step 9 Go to Step 6
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).
Refer to 6E-95 page.
3. Disconnect the MAF sensor connector.
4. Check the circuit for open circuit.
Was the problem found?

B39
Breaker BoxE-63






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?
E-63 E-61(B)







-

Repair faulty
harness and
verify repair

Go to Step 7

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-157
Step Action Value (s) Yes No
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?
E-63
V




Less than 1V
Go to Step 8
Repair faulty
harness and
verify repair
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?
E-63
V




Less than 1V
Go to Step 11
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 -

6E-158 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0112 (FLASH CODE 23) INTAKE AIR
TEMPERATURE (IAT) SENSOR LOW INPUT

RUW46EMF000101

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)
23 P0112 A Intake Air Temperature
Sensor Low Input
IAT sensor output voltage is below 0.08V. The ECM use 40C conditions as
substitute.

CIRCUIT DESCRIPTION
The intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine. The Engine Control Module (ECM) applies 5
volts through a pull-up resistor to the IAT sensor. When
the intake air is cold, the sensor resistance is high and
the ECM will monitor a high signal voltage on the IAT
signal circuit. If the intake air is warm, the sensor
resistance is lower, causing the ECM to monitor a lower
voltage. DTC P0112 will set when the ECM detects an
excessively low signal voltage on the intake air
temperature sensor signal circuit.
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 IAT display on the Tech 2 while moving
connectors and wiring harnesses related to the IAT
sensor. A change in the IAT display will indicate the
location of the fault.
If DTC P0112 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-159
Diagnostic Trouble Code (DTC) P0112 (Flash Code 23) Intake Air Temperature
(IAT) Sensor Low Input

Step Action Value (s) Yes No
1
Was 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 By Priority" in "F0:
Diagnostic Trouble Code".
Is the DTC P0112 stored as "Present Failure"?
- Go to Step 3 Refer to
Diagnostic Aids
and Go to Step 3
3
1. Using the Tech2, ignition "On" and engine "Off".
2. Select "Clear DTC Information" with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the "F5: Failed
This Ignition" in "F2: DTC Information"
Was the DTC P0112 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 IAT sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
E-60(A)
E-61(B)
E-63






- Verify repair Go to Step 5
5
Remove the MAF & IAT sensor assembly and visually
check.
Was the problem found?
- Go to Step 8 Go to Step 6

6E-160 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
6
Using the DVM and check the IAT sensor.
1. Ignition "Off", engine "Off".
2. Disconnect IAT sensor connector.
3. Measure the resistance of IAT sensor.
Does the tester indicate standard resistance as shown
in the following table?
MAF & IAT Sensor






Temperature (
C) Resistance ()
(Approximately)
-20 15230
0 5760
20 2480
40 1185
60 584
80 332
100 183
120 11 9Standard
resistance Go to Step 7 Go to Step 8