Ny truck keeps throwing a p0113 code "intake air temp. circuit high" i can only get 25 pound of boost its sluggish of the start and it surges it basically has no power i took it to my dealer today and they changed my icp sensor,pigtail and fixed a ground wire on the ficm.Total bill 700 i picked it up right at closing and it still runs the same as when i dropped it off any ideas i had my AE hooked up a local diesel shop told me that when the koeo the IAT voltage should read 0 at an idle 1.6v mine is reading 2.26v at koeo and 2.6v at an idle i changed out my MAF sensor with a spare i had and it reads 4.97v all the time the tech i talked to said it was a wiring issue and not the sensor sorry this is so long but i have been trying to figure this out for a week and i really need to get this figured out quickly

 

You're probably going to have to start tracing wires. The VRef wire from the PCM to the MAF sensor for IAT1 is a grey wire. It terminates at the most rearward connector on the PCM, on the bottom row of wires. You'll see it in the MAF connector.

The IAT1 return is grey/red and is shared with a few other sensors. You will see it on the MAF sensor connector and it will terminate on the same PCM connector as the grey wire, but in the third row. If you trace this wire out, you will see the grey/red go in different directions through the harness as it's common to MAP,WIF, baro, and APP 1.

To get started, disconnect the batteries and start checking continuity between the the sensor(s)and PCM connector. Hopefully the problem makes itself evident with some basic testing.

 

i will try that my grey wire on the maf sensor was rubbed through it looks loke it was rubbing on the dipstick tube i sliced the insulation off and couldnt find anything broke is it possible that it shorted something out in the pcm

 

Anything is possible, but if there were a damaging short, chances are you wouldn't be seeing any any voltage on the circuit. The contact between grey and the dipstick tube could cause the constant 4.97 as the Vref signal found it's way to ground through the dipstick.

With koer, pull the MAF sensor connector and you should see 4.97v between the grey and grey/rd wires. If you don't, probe from grey to the PCM case and re-check. Check continuity between gray/red and the PCM case, it should ring out. Check continuity between grey and PCM case and it should not. If grey to PCM case does ring out, disconnect the batteries and unplug the rear PCM connector. Ring out grey from the appropriate pin in the PCM connector to the MAF connector pin to prove that the problem is between the two connectors.

 

Ive seen this section of harnees get melted/ fused together from brake fluid and p/s fluids before. it seems to happen at the take out in the harness at the fender well.

 

i just checked the voltage at the grey and grey&red wires at the maf connector with koer and got 4.97v does this mean the sensor is shot its kinda wierd b/c with the one maf sensor plugged in its reading 2.29v and the other one i have reads 4.97v i dont want to buy a 400 sensor until i know thats the problem

 

Reading between the grey and grey/red proves the circuit is intact. FWIW, Here's the 6.0l bible IAT1 summary..

With the engine off, check the resistance across each of your sensors(outside pins). The spare sensor reading 4.97 is probably shot and will read open. The 2.29 doesn't look too bad depending on what the ambient temp is where you are at. What is the resistance across that sensor when it's cold(mine reads 52.9k ohms at about 52*f)? Another problem is that any resistance introduced into the circuit(wiring fault, not short) will increase the voltage of the circuit. Doesn't sound right, but that's the way these circuits are designed. More resistance from the sensor/or wiring will result in higher voltage measured by the PCM. After you get a resistance measurement across your sensor, plug the MAF back in, disconnect the batteries, disconnect the appropriate PCM connector, and measure the resistance between grey and grey/red through the PCM connector with the sensor installed. If there is a decent difference between the 2 measurements, suspect the harness. You could then disconnect the sensor, and measure resistance of each path from the PCM connector to MAF connector to try and isolate which leg is the problem. Did you check the area cheezit suggested?

I never like to suggest anyone spend $400 on a sensor that may not be the problem. It would be nice if you had a PSD buddy and could borrow his MAF to test on your truck, and then you could eliminate that as a cause. These are tough problems to diagnose over the computer. There's no guarantee that this IAT1 problem is causing your running issue either.

 

i am going to check were cheezit is talking about today i have spilled quite a bit of power steering oil down there i checked the resistance on the sensor i cant remember what it was but when i checked it plugged in it was only 12k there time to do some more digging i am going to try and borrow a maf sensor today so i can rule that out as well thanks for now

 

spent 4 hours tracing wires and never found a thing cleared the codes after 200km of driving the only one that came back was p0100 maf circuit the truck is running great it just seems to be lacking power i forgot to mention i have a boost fooler installed but i already tried disconnecting it and it didnt make a difference at all i will be talking to my dealer about it this morning to see what they think but any more ideas would be great i know this is a difficult thing to diagnose on the computer but i really appreciate all the help so far thanx guys