Diagnostic Aids
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
To locate an intermittent problem, use scan tool to monitor MAF sensor with ignition on, engine off. Wiggling wires while watching for a change in MAF sensor voltage may locate area where an open or short to ground in wiring could lie.
If ECM looses MAF sensor signal, it will calculate airflow based on MAP, engine speed and TP sensors.
MAF, A/C pressure, fuel tank pressure and APP sensor 1 sensors share the same 5-volt reference supply (5-volt reference "A").
CMP, ECT, IAT, and MAF sensors share the same sensor return circuit.
A direct short to voltage on Black wire (circuit 2761) may cause internal damage to the ECM ground trace, or open the sensor element in the ECT and/or IAT sensor.