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Well my mind is officially boggled... have a 2014 Dodge 4500 with the 6.7 diesel. Has P0113 intake air temp circuit high, it is a hard code: returns as soon as it is cleared. Looking at the data PID the voltage is fixed 5.0V. Now the sensor is a combined MAF and temp sensor. 4 wires, a 5v ref, low ref, MAF signal and Temp signal. Now from what I read in Scanner Danner's book, thermistors use a combined power/signal wire and it measures the drop to ground. So, with the sensor unplugged I have 5v on the reference, no meaningful voltage on the ground (and 12v when connected to power), no volts on the MAF and 5v on the temp wire. With the sensor plugged in, backprobing the wire I have the same for the first two but the MAF has 3v or something like that and the temp shows 1.5v. PID is still stuck at 5v. I back-probed the wire at the PCM and have 1.5v there as well. So.... this leads me to believe that there is nothing left but the PCM correct? The MAF still appears to function correctly and we tried a new sensor with no avail. My first time having to call a PCM so I just want to make sure I get this right!
Ok I will double check the ground, because I don’t remember exactly what it was except for that it was very low and that my meter auto ranged the the MV scale. But, according to my DVOM the sensor is working fine! With the sensor out of the intake, if I backprobe the wire 1.5V if I put my hand around the sensor or blow some warm air on it I can watch the voltage change! But nevertheless the PID is still fixed at 5v. The sensor functioning this way and no problem with any other sensors would seem to indicate that the grounds are ok right?
The problem is that the PID is stuck at 5v but that actual voltage at the sensor is less, like the sensor is working but the PCM isn’t receiving that data
And you said that is what you are reading at the ECM on that pin? I was thinking the same as monde before but I think with that reading at the ECM, it wouldn't change the 5v reading in the pid. You could try bringing it down with a test light to battery ground and wee if the pid voltage changes, but I don't think it will in this case.
Yes, 1.5V at the sensor and ECM both just not on the scanner. No I haven’t tried a different scanner I can try that, but considering that it is setting the code for high voltage on that circuit it would make sense that the PID is stuck at 5v. I will definitely check powers and ground before finally condemning the PCM.
I will definitely get the fix to you guys whenever I figure it out, but I don’t think the boss is in a super huge rush, especially if it is something as big as the PCM.
So unplug the sensor and jump the signal and return of the IAT sensor circuit to see if the data pid changes value. If it does, you've eliminated the circuit and the computer. If it doesn't, then the sensor is not the issue.
