Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the B75C Multifunction Intake Air Sensor.
- Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 Ω between the ground circuit terminal 7 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
- If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
- If the circuit tests normal and the fuse is open, test all the components connected to the circuit and repair or replace as necessary.
- Ignition ON, test for 4.8-5.2 V between the signal circuit terminal 6 and ground.
- If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
NOTE:If the signal circuit is shorted to a voltage the ECM or the sensor may be damaged.
- Ignition OFF, connect the leads of the J 38522
Variable Signal Generator as follows:
- Red lead to the signal circuit terminal 6 at the harness connector
- Black lead to ground
- Battery voltage supply lead to B+
- Set the J 38522
Variable Signal Generator to the following specifications.
- Signal switch to 5 V
- Duty Cycle switch to 50 % (Normal)
- Frequency switch to 5 KHz
- Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4,950-5,050 Hz.
- If the parameter is not within the specified range, replace the K20 engine control module.
- If all other circuits test normal, replace the B75C Multifunction Intake Air Sensor.