Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Canyon and 2010 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: All electrical components and accessories must be turned OFF and allowed to power down.

Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
Ignition OFF, all vehicle systems OFF, this may take up to 2 min, test for less than 5 Ω between the ground circuit terminal B 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 C 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 terminal A 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. Connect the battery voltage supply to B+, and the black lead to ground.
Set the J 38522 signal to 5 volts, the Frequency to 5K, and the Duty Cycle to Normal.
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 MAF Sensor parameter is not within the specified range, replace the ECM.
If all circuits test normal, replace the MAF sensor.