Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 126

6E–108

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

The ECM supplies 5 volts signal to the IAT sensor
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the air temperature
is cold, and it will be low when the air temperature is hot. 
The output voltage excessively high or low, DTC P0110
(Symptom Code 1) or P0110 (Symptom Code 2) 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  “Intake Air Temperature” display on the Tech2
while moving connectors and wiring harness related
to the sensor.

Diagnostic Trouble Code (DTC) P0110 (Symptom Code 1) (Flash Code 23) 

Intake Air Temperature (IAT) 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 As Stored By ECU” in

“F0: Diagnostic Trouble Codes”. 

Is the DTC P0110 (Symptom Code 1) 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 P0110 (Symptom Code 1) 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?

—

Verify repair

Go to Step 5

5

Visually check the IAT sensor. 
Was the problem found? 

—

Go to Step 12

Go to Step 6

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4JH1 ENGINE DRIVEABILITY AND EMISSIONS

6E–109

6

Using the DVM and check the IAT sensor.

1. Ignition “Off”,  engine “Off”. 

2. Disconnect MAF & IAT sensor connector. 

3. Measure the resistance of IAT sensor. 

Does the tester indicate standard resistance as shown
in the following table? 

Standard 

resistance

Go to Step 7

Go to Step 12

7

Using the DVM and check the IAT sensor signal
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?

Approximately 

5.0V

Go to Step 10

Less than 1V: 

Go to Step 8

More than 

specified value: 

Go to Step 9

8

Repair the open circuit between the ECM and IAT
sensor. 
Was the problem solved?

—

Verify repair

Go to Step 14

Step

Action

Value(s)

Yes

No

Temperature (°C)

Resistance (

Ω) (Approximately)

-20

14210

0

5402

20

2343

40

1131

60

596

80

338

100

203

1

2

3

5

4

1

3

IAT Sensor

1

V

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4JH1 ENGINE DRIVEABILITY AND EMISSIONS

9

Repair the short to voltage circuit between the ECM
and IAT sensor. 
Was the problem solved?

—

Verify repair

Go to Step 14

10

Using the DVM and check the IAT sensor ground
circuit.

1. Ignition “On”, engine “Off”. 

2. Disconnect the MAF & IAT sensor connector. 

3. Check the circuit for short to power supply circuit. 

Was the DVM indicated specified value?

Less than 1V

Go to Step 11

Repair faulty 
harness and 

verify repair

Step

Action

Value(s)

Yes

No

1

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3

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4JH1 ENGINE DRIVEABILITY AND EMISSIONS

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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-73

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 immobiliser system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobiliser System-ECM replacement” for
the ECM/Immobiliser linking procedure.

—

Verify repair

—

Step

Action

Value(s)

Yes

No

92

3

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