Pace Arrow: Code P0112

[Dash48]

Okay family I need some help I am at the end of my rope I have a 2000 Pace arrow vision 36-ft motorhome on a Ford f-53 chassis I have done everything possible to try to diagnose the problem my motorhome is throwing a IAT low sensor code. Like most backyard mechanics I replace the air filter the flow sensor indicator check the wiring harness check the voltage coming out of the harness to the sensor connector disconnected the battery overnight control the vehicle at 55 mi an hour down to 30 mph due to the engine fluctuating high racing speed to low racing speed after about 10 minutes on the road. I have read and watched many YouTube videos understanding that it is a gas and air mixture that the computer has to understand to allow the engine to function at its maximum performance it is a Ford V10 6.8 I believe engine again I met a loss I checked all the fuses wiring harness air filter canister what else is left to check? Is there a recall I know there are two holes on the canister let the air flow through into the air filter into the chamber that goes to the carburetor which is fuel injected what am I missing? I'll be more than happy to talk to anybody on the phone 281-731-7126 I have went to the Fleetwood manufacturer dealership at Holiday world they do not work on engine camping world does not work on engines ron hover does not work on engine so who's left to help me with my engine problem. James in Houston Texas

[tderonne]

Did you type that right, "P0112"? 112 is an Intake Air Temperature (IAT) code. While it's located within the MAF sensor, it seeing the wrong temperature, not airflow.

Do you have any kind of scan tool? Maybe a ScanGauge? You shoule be able to display IAT with either, see what it's reading in real time.

[Unplanned Tourist]

X2 for the ScanGuageII. You can monitor the IAT in real time.

[Dash48]

I have an actron 2 scan diagnosed and you are correct in it being the intake air temperature I was trying to correct that I just posted a few minutes ago what do you think the problem could be I'm not sure how to use the scan diagnosis correctly

[dceggert]

ForScan is the way to go. The software package is open source and loads on a windows laptop or tabletPC (my favorite). You can get a bluetooth or usb tool for the OBD port for pretty reasonable ($60 or less as described at the ForScan website). It will access all the can channels (including the high speed channel with the RCM on my 2017 Fusion that other readers would not read), read and clear codes, allow monitoring, and in some cases you can make configuration changes.

https://forscan.org/

[Gary RVRoamer]

If you need engine help, FORD works on their engines so any Ford dealer should be able to help (for a price, of course).


Doesn't the 112 code means the sensor reading is out of range on the low side, which often means a grounded-out wire? sorry, I'm mostly a GM guy so not real swift on Ford codes and issues.

[Dash48]

Thanks Gary I live on the west side of Houston Texas and most of the Ford dealers have already declined taking my Ford f-53 motorhome to their location I am going to do it yourself backyard mechanic so I will try to retrace the harness wiring to see if there was a ground issue but you are correct I'm having a sensory code that is reading on the low side so I need to find where I'm having a ground issue thanks for your help

[meebarb]

Dash48,
Could you make it to Brenham with it? Ford dealer there is supposed to work on Class A's. Appel Ford 979-836-3659. Maybe at least give them a call and see if you can talk to a tech?

[robertkathy]

9 times out of 10 the IAT sensor is bad. replace the mas

[tderonne]

The IAT will read -40°C if it's an open circuit. A scan tool will tell you if it's doing that all the time.

The IAT sensor is "grounded" directly to the PCM. It's part of the MAF sensor.

Couple diagrams:
http://1999southwind.com/DOWNLOAD/E1I02501.pdf

http://1999southwind.com/DOWNLOAD/E1I02507.pdf

The MAF sensor is on page 25-1. The IAT sensor is between pins #1 and #6. Pin #39 on the PCM is the IAT signal, and pin #91 is signal return (ground). You can follow the wiring on the two pages linked above.

[Gary RVRoamer]

I live on the west side of Houston Texas and most of the Ford dealers have already declined taking my Ford f-53 motorhome to their location

Somewhere around Houston there will be a Ford dealer that sells and services the larger Ford trucks, e.g. F450/F550/F750. They will know how to handle an F53 as well.


But I understand the DIY approach and would probably be doing the same myself.

[Dash48]

I'll give them a call in Austin and see what their hourly rate is I did get a Ford dealer in Rosenberg called legacy they charge $160 an hour but I'm trying to diagnose and fix the problem because I'm a disabled veteran now to fix income so I don't have a lot of extra cash to just throw out there which I do have about 40 years of background in mechanics

[Dash48]

Thanks for the suggestion Gary I'll look into it I also got a good lead from TD Ron who suggested I track my wiring harnesses they are located under the brake system inside the cab I'm going to disconnect them look at all the pins and then put them back in place I got two diagrams so we'll see if I can troubleshoot and find what darn mouse got into my cheese LOL thanks for all the info I'll post an update what I find I replace the sensor and a brand new air filter in the last 5 days in hopes that would rectify the problem still need to trace the wiring harnesses for any broken wires or ground issues on another note. I'm trying to troubleshoot my own Marquis 5500 generator it was running but all of a sudden there is water coming out of the exhaust it runs for one minute and then quits I read somewhere where the gasoline can leave a lot of water deposit after the carbon has burned however my generator won't stay running just another day in the life of RVing

[Dash48]

Originally Posted by tderonne

The IAT will read -40°C if it's an open circuit. A scan tool will tell you if it's doing that all the time.

The IAT sensor is "grounded" directly to the PCM. It's part of the MAF sensor.

Couple diagrams:
http://1999southwind.com/DOWNLOAD/E1I02501.pdf

http://1999southwind.com/DOWNLOAD/E1I02507.pdf

The MAF sensor is on page 25-1. The IAT sensor is between pins #1 and #6. Pin #39 on the PCM is the IAT signal, and pin #91 is signal return (ground). You can follow the wiring on the two pages linked above.

Thanks for the diagram TDeronn this is very helpful I will trace the wiring harness for the IAT 39 and also number 91 ground wire and see what I find I really appreciate all you guys help I am a disabled veteran on a fixed income so it helps so much to be able to troubleshoot and fix these problems at home