Component Testing

IAT Sensor 1

1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: B75C Multifunction Intake Air Sensor
3. Test for 49 to 49, 882 ohms between the test points: Signal terminal 1 & Low Reference terminal 3
   • If not between 49 and 49, 882 ohms 

     Replace the component: B75C Multifunction Intake Air Sensor

   • Go to next step: If between 49 and 49, 882 ohms 
4. Verify the value is within the range listed in the table: Temperature Versus Resistance - Intake Air Temperature Sensor
   • If not in the specified range 

     Replace the component: B75C Multifunction Intake Air Sensor

   • Go to next step: If in the specified range 
5. Test for infinite resistance between the test points: Each terminal of the component & The component's housing
   • If less than infinite resistance 

     Replace the component: B75C Multifunction Intake Air Sensor

   • Go to next step: If infinite resistance 
6. All OK.

IAT Sensor 2

NOTE:

Circuit/System Testing must be performed before proceeding with Component Testing.

1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: B75C Multifunction Intake Air Sensor
3. Install the special tool: EL-38522 Variable Signal Generator
   • Black lead @ Ground
   • Battery Cable Clip@Battery
   • Red lead @ Signal circuit terminal 8
   • Set the voltage to 5 V
   • Set the frequency to 250 Hz
   • Set the duty cycle to 50%
4. Ignition - On/Vehicle - In Service Mode
5. Verify the scan tool parameter:
   • IAT Sensor 2 = 248 to 252 Hz
   • IAT Sensor 2 = 70 to 76°C (160 to 166°F)
   • Intake Air Humidity Sensor = 48 to 52%
   • If not in the specified range or does not change 
   1. Ignition/Vehicle - Off
   2. Disconnect the appropriate electrical connector: @ K20 Engine Control Module
   3. Test for less than 2 ohms between the test points: Signal circuit terminal 8 @ B75C Multifunction Intake Air Sensor & Circuit terminal 60 X1 @ K20 Engine Control Module
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K20 Engine Control Module
   • Go to next step: If in the specified range and changes 
6. Replace the component: B75C Multifunction Intake Air Sensor