FIXED Ford iat sensor

I need help. I have a 2016 ford f59, someone repaired the maf/iat and I dont know if they wired it right. The iat is reading between -38 and -40°. I have swapped the sensor out with 2 known good sensors and also pcm. I cant find the proper wiring diagram. I have a ground, 12v and a 5v ref.

I don't know what an F59 is, but if its like a Super Duty, here's the pin out.
For what it's worth I'd be willing to bet just about anyhthing Ford of that era has the same pin configuration

Be gentle, my first time using the forums. I'll give it a shot though.

First thing's first. I'd absolutely cut those connectors and clean them up. If you have a bad connection in there, it won't matter how many sensors you put in that bad boy. You could always just do a simple resistance check on the wires but I'd probably argue that it's easier to fix them / clean them up right then trace to test resistance the right way.

Second, I'm lucky enough to have access to wiring diagrams for that beast.



Intake air temp is fed back to the computer on the grey wire, from what I can tell. So, start there, would be my guess.

It appears the fuel pump relay is feeding power to the circuit and resistance across the intake air temperature sensor lowers voltage. The computer receives this lowered voltage and calculates actual temperature off of that.

I think we can make a couple of assumptions here. If you were to disconnect the sensor, you're removing voltage from that system all-together. That would probably explain the -40 reading, honestly. I'd bet if you were to backprobe that wire at the PCM and supply voltage, you'd see the actual temperature reading go high in response.

My money is on that grey wire being repaired incorrectly. You probably have a break in the wire and it's not receiving proper voltage from the intake air temperature sensor.

Also....



Verify the wiring is actually correct while your at it. Picture of how she's supposed to be wired attached.

As I said, I'm new to this. If anyone else wants to chime in in case I'm wrong, please do so. Just giving my take on it

Thank you very much for your reply. Your diagram was very helpful . Thank you for that. Im finding 5v on the gray wire with the maf/iat connector unplugged. I pulled the connector from the pcm and im still finding 5v on the #27 terminal. Im not understanding why i have voltage coming out of the pcm on a wire that should be receiving the signal.

Chadagore1 wrote: Im finding 5v on the gray wire with the maf/iat connector unplugged. I pulled the connector from the pcm and im still finding 5v on the #27 terminal. Im not understanding why i have voltage coming out of the pcm on a wire that should be receiving the signal.

It'll be a pull down signal. Current limited 5V from the PCM that gets pulled down towards ground by the IAT. Then the PCM reads what voltage the signal gets pulled down to and uses that to figure IAT temperature.

What I'd do is plug the PCM back in but leave the MAF/IAT sensor unplugged. Then hook up a scan tool KOEO and pull up the IAT PID in global. It should be reading pegged either hot or cold unplugged. Then ground the grey wire with a test light and see if the PID changes to the other extreme.

I disconnected the maff/iat and grounded out the iat with my test light and it did jump to 266°. I also jumped the iat terminal to the ground terminal and i got the same result.

Problem sloved! The original maf sensor was replaced with the wrong part#. Although i changed out the sensor twice, i was going off the sensor that was wrong to begin with. I called ford and confirmed it was the wrong part number. I picked tge riggt one up from the dealership and bingo its fixed. Thanks for the help.

Nice job. Thank you for posting the fix!