Intake Air Temperature Sensor, Checking

Observe all safety precautions: SAFETY PRECAUTIONS 

View clean working conditions: CLEAN WORKING CONDITIONS 

Prior to repair work, perform a preliminary check to verify the condition. Refer to PRELIMINARY CHECK .

Special Tools And Workshop Equipment Required 

• Multimeter.
• Wiring diagram.

Test Procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start Diagnosis 

-- Connect the scan tool.

-- Engine must be at room temperature.

-- Switch the ignition On.

-- Using the scan tool, check the intake air temperature:

Diagnostic text		Specified value
Intake Air Temperature (IAT)		approx. ambient air temperature

If The Specified Value Was Obtained: 

-- Fault is intermittent. Check for proper connection, damaged wiring or loose terminals.

If The Specified Value Was Not Obtained: 

Checking internal resistance

-- Disconnect the Charge Air Pressure Sensor/IAT sensor -G31/G42- electrical harness connector.

-- Using a multimeter, check the Charge Air Pressure Sensor/IAT sensor -G31/G42- terminals 1 to 2 for resistance.

Use the chart below for the specified values:

Specified Values: 

IAT Temperature vs Resistance
Temp (C)	min. value ohms	max value ohms
- 50	31811	37560
- 45	22941	26863
- 35	12415	14289
- 25	6958	7880
- 15	4036	4495
0	3120	3442
15	2422	2655
25	1519	1623
35	968	1031
45	629	676
55	419	455
65	286	314
75	195	217
85	136	155

If The Specified Value Was Not Obtained: 

-- Replace the Charge Air Pressure Sensor/IAT sensor -G31/G42- Refer to the Repair information.

If The Specified Value Was Obtained: 

-- Turn the ignition switch ON

-- Check the voltage from terminal 1 to terminal 2 of the IAT connector.

Specified value: Min. 4.40 V

If The Specified Value Was Not Obtained: 

Checking Wiring 

-- Remove the Engine Control Module (ECM) -J623-.

-- Using a multimeter, check the Charge Air Pressure Sensor/IAT sensor -G31/G42- electrical harness connector to the Engine Control Module (ECM) -J623- electrical harness T94 connector for resistance. Refer to Appropriate Wiring Diagrams for Pin locations.

Charge Air Pressure Sensor/IAT sensor -G31/G42- electrical harness connector terminal	Engine Control Module (ECM) -J623- electrical harness connector T94 terminals
1	66
2	30

Specified Value: 1.5 Ω Max. 

If The Specification Was Not Obtained: 

-- Check the wiring for a short circuit to each other, Battery positive, Ground or high resistance.

-- If necessary, repair the faulty wiring connection.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

If No Malfunction Is Detected In The Wiring And The Voltage Readings Were Not Correct: 

-- Replace the Engine Control Module (ECM) -J623-. Refer to the appropriate Service Information for removal and installation procedures.

Final Procedures 

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .