DTC 24
Open/Shorted Intake Air Temperature Sensor Circuit:
Intake Air Temperature Sensor Circuit:
Circuit Description:
The intake air temperature (IAT) sensor is a thermistor (a variable resistor that changes along with outside air temperature changes) in series with a fixed resistor within the engine control module (ECM). The IAT sensor measures the temperature of the air entering the intake manifold. The ECM applies 5 volts to the sensor. The ECM monitors the voltage across the IAT sensor and converts it into a temperature reading. When the outside air temperature is cold, the IAT sensor resistance is high, and when the outside air temperature is warm, the IAT sensor resistance is low. Therefore, when the air temperature is cold the ECM will receive a high voltage input. and when the air temperature is warm the ECM will receive a low voltage input.
DTC 24 will set if either of the following conditions are met for at least 0.50 seconds:
(1) Voltage input at the ECM indicates a very low air temperature.
(2) Voltage input at the ECM indicates a very high air temperature.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
1. This checks for an open or short to ground in the YEL/BLK wire between the ECM and IAT sensor and for a faulty ECM.
2. This checks for an open in the BRN wire between the ECM and the IAT sensor and for a faulty ECM.
3. This determines if the problem is a faulty IAT sensor or ECM.
Diagnostic Aids:
A "shifted" (mis-scaled) sensor could result in poor driveability complaints. Measure the resistance of the IAT sensor according to the diagnostic aids chart on the diagnostic chart. If DTCs 22, 31 and 41 are also set, problem is open sensor ground circuit.
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.