Circuit/System Testing
- Verify the integrity of the entire air induction system by inspecting for the following conditions:
- Any damaged components
- Loose or improper installation
- An air flow restriction
- Any vacuum leaks
- Water intrusion
- In cold climates, inspect for any snow or ice buildup
- The MAF sensor element for contamination
- Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the ground circuit terminal C 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 B and ground.
- If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
- Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A 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 ECM.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal A at the MAF/IAT sensor harness connector. See Special Tools . Connect the battery voltage supply to the B+, and ground the black lead.
- Set the J 38522 signal switch to 5 volts, the Frequency switch to 5K, and the Duty Cycle switch to Normal. See Special Tools .
- Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4,950-5,025 Hz.
- If the MAF Sensor parameter is not within the specified range, replace the ECM.
- If all other circuits test normal, test or replace the MAF sensor.