Component Testing

Multifunction Intake Air Sensor

1. Test the Intake Air Humidity Sensor by varying the air humidity in the intake duct near the sensor, while observing the scan tool Intake Air Humidity Sensor parameter. The parameter should change and be within 5 - 95%.
   • If not within the specified range 

     Replace the B75C Multifunction Intake Air Sensor.

   • Go to next step: If within the specified range 
2. All OK.

Testing with EL-38522-A

NOTE:

In-correct diagnosis will result if Circuit/System Testing is not completed before performing the following test.

1. Perform the following test using a EL-38522-A  Variable Signal Generator or equivalent, if available.
2. Ignition Off, connect the leads of the EL-38522-A  Variable Signal Generator as follows:
   1. Red lead to the signal circuit terminal 8 at the harness connector
   2. Black leads to ground
   3. Battery voltage supply lead to B+
3. Set the EL-38522-A  Variable Signal Generator to the following specifications.
   • Signal switch to 5 V
   • Duty Cycle switch to 50% (Normal)
   • Frequency switch to 250 Hz
4. Ignition On.
5. Verify the scan tool IAT Sensor 2 parameters listed below are within the ranges listed below:
   • IAT Sensor 2 is between 248 - 252 Hz
   NOTE:

   Changing the frequency should cause a warmer or colder IAT 2 temperature.

   • IAT Sensor 2 is between 70 - 76°C (160 - 166°F)
   NOTE:

   Increasing or decreasing the duty cycle should have an inverse affect on humidity.

   • Intake Air Humidity Sensor is between 48 - 52%
   • If a parameter is not within the specified range 
   1. Ignition Off, remove the EL-38522-A  and disconnect the harness connector at the K20 Engine Control Module.
   2. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
   • Go to next step: If all the parameters are within the specified range 
6. All OK.