Check to see if these wires have 12 volts at the mass air flow sensor using a multimeter. This voltage will only be applied for approximately 5 to 30 seconds after the engine has been shut off ...

He decided to replace this with a modern mass air flow (MAF) sensor instead, and documented the process online.

GM has issued a recall for certain units of the Chevy Low Cab Forward 3500 and 4500 models due to an issue with the mass air flow (MAF) sensor.