Intake Air Temperature Sensor, Checking: Notes

NOTE:

The Manifold Absolute Pressure sensor and the Intake Air Temperature sensor are combined as a unit and are serviced as an assembly.

Use only gold-plated terminals when servicing terminals in the electrical harness connector of the MAP / IAT sensor -G71 / G42-.

Special Tools And Workshop Equipment Required

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 MAP / IAT sensor -G71/G42- electrical harness connector.

-- Using a multimeter, check the MAP / IAT sensor -G71/G42- terminals 1 to 2 for resistance.

Use The Chart Below For The Specified Values:

Specified Values:

IAT Temperature vs Resistance (approximate)
Temp (C)	min. value ohms	max value ohms
- 40	31811	37560
- 35	22941	26863
- 25	12415	14289
- 15	6958	7880
- 5	4036	4495
0	3120	3442
5	2422	2655
15	1519	1623
25	968	1031
35	629	676
45	419	455
55	286	314
65	195	217
75	136	155

If The Specified Value Was Not Obtained:

-- Replace the MAP / IAT sensor -G71 / G42-.

If The Specified Value Was Obtained:

-- Continue the test according to the following table:

Indicated	Cause	Test
Between -39 to 139 °C	Component or wiring	Checking Component and wiring
-40 to -46 °C	Open circuit or short circuit to (B+)	TESTING IF DISPLAY IS - 40 °C
140 °C	Short circuit to Ground	TESTING IF DISPLAY NEAR 140 °C: