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Home >> GMC >> 1998 >> Forward Control 6.5 F >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Engine Controls - System & Component Testing - 7.4L) >> Engine Sensors & Switches >> Engine Controls - System & Component Testing - 7.4L >> Intake Air Temperature (IAT) Sensor

Intake Air Temperature (IAT) Sensor

WARNING: This page is about a different variant/trim than selected.

If an IAT sensor-related code is present, perform appropriate DTC test. See TESTS W/CODES - 7.4L article. An out-of-calibration sensor may not set a trouble code. Use following procedure to test calibration. Disconnect IAT sensor harness connector. Measure resistance between IAT sensor terminals. Sensor resistance should be as specified. See IAT SENSOR RESISTANCE VALUES  table. Resistance should be high when air temperature is cold and drop as air temperature warms. With vehicle sitting overnight, IAT sensor and coolant sensor should have close to the same resistance reading.

IAT SENSOR RESISTANCE VALUES

Temperature °F (°C) Ohms
212 (100) 177
158 (70) 467
104 (40) 1459
68 (20) 3520
32 (0) 9420
5 (-15) 21,450
-40 (-40) 100,700
Fig 1: Identifying MAP, MAF & CKP Sensor Harness Connector Terminals
G98J00868Courtesy of GENERAL MOTORS CORP.
NOTE: Ensure oil is okay before performing engine oil level sensor/switch diagnosis.