I got this low input voltage code on my OBD tool, and my 97 F150 runs rough. I put in a salvage engine last summer. The Chilton manual says I should read battery voltage at the connector, so I am guessing that means that I should read full battery voltage, it does not give a specific number.
My readings are 5.48V.
Any ideas?

 

The RED wire at the MAF should be full battery voltage. Is that the one you're checking?

Steve

 

According to the Chilton manual I am. I guess I need to verify pins to wires?

 

The wire color code is adequate. That RED wire should have full battery voltage on it. If it doesn't the MAF, will not function properly.

Steve

 

It seems that my Chilton manual (2003 printing) is wrong (perhaps a typo from the following step) with regard to the terminal names; page 6-8, Fig. 4.29. What is called Gnd, is part of the MAF signal system . The real voltage gound referance should be the Processor PCM Power Ground. I got battery voltage between it and the B+ voltage terminal. What the voltage is under actual driving conditions is, I really don't know. The engine would die at idle more often that not. I guess that it could be that the wires from the harness connector to the actual MAF sensor are messed up. This trouble developed shortly after I took the truck in for an oil change and they took the air cleaner apart.

MAF was reading 0 lbs/sec at any speed when I drove it to the shop.