Powertrain Controls - ECM/PCM

DTC 47 Intake Air Temperature (IAT) Circuit Low (High Temperature Indicated):

Intake Air Temperature (IAT) Circuit Low (High Temperature Indicated):

CIRCUIT DESCRIPTION
The Intake Air Temperature (IAT) sensor is a thermistor that controls signal voltage to the Powertrain Control Module (PCM). When the air is cold, the sensor resistance is high, therefore the PCM will see high signal voltage. As air warms, sensor resistance becomes less and voltage drops.

DIAGNOSTIC TROUBLE CODE (DTC) 47 WILL SET WHEN
^ Engine coolant less than 38°C (1OO°F).
^ Intake air temperature is greater than 96°C (205°F) for 2 seconds.

ACTION TAKEN (PCM will default to)
Poor performance during cold weather operation.

DTC 47 WILL CLEAR WHEN
The fault condition(s) no longer exist.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step determines if DTC 47 is a hard failure or an intermittent condition.
2. This test will determine if CKT 472 is shorted to ground.

DIAGNOSTIC AIDS
Check harness routing for a potential short to ground in CKT 472.
Tech I scan tool displays intake air temperature in degree centigrade. A faulty connection or an open in CKTs 452 and 472 will result in a DTC 47.
If DTC 33 is intermittent, refer to Intermittents. - Intermittent Malfunctions
The "Temperature to Resistance Value" scale may be used to test the intake air temperature sensor at vanous temperature levels to evaluate the possibility of a "skewed" (mis-scaled) sensor. A "skewed" sensor could result in poor driveability complaints.