Circuit/System Testing

IMPORTANT: The test lamp is used to load the circuit. Use the J 35616-200 for this test. If the J 35616-200 is not available, use a test lamp that measures more than 20 ohms.

With the ignition ON, the engine OFF, and the MAF sensor harness disconnected, connect a test lamp between the ignition 1 voltage circuit and a good ground. Measure the battery voltage and record the measurement. Measure for battery voltage between the ignition 1 voltage circuit at the test lamp probe end and a good ground.
- If the voltage is not within 1.5 volts of battery voltage, repair the high resistance in the circuit.
With a DMM, measure for a voltage range of 4.8-5.2 volts between the MAF sensor signal circuit and a good ground.
- If the voltage is less than 4.8 volts, test the circuit for a high resistance.
- If the voltage is within the specified range, test the circuit for a short to the IAT signal circuit or to any other 5-volt reference circuit.
Turn OFF the ignition and all electrical accessories. Allow sufficient time for the control modules to power down before taking a resistance measurement.
Measure for a resistance of less than 5 ohms between the ground circuit of the MAF sensor and a good ground.
- If the resistance is more than 5 ohms, repair the high resistance in the ground circuit.
Connect the J 38522 to the vehicle. See Special Tools . Refer to Component Testing.
Start the engine and observe the MAF Sensor parameter for a proper range of 4,950-5,025 Hz.
- If the MAF Sensor parameter is not within the specified range, replace the ECM.
- If the MAF Sensor parameter is within the specified range, replace the MAF sensor.