Ambient air temperature sensor high voltage

[Ross Bezvy]

Hi.
I have a 2009 ProStar Premium with Cummins ISX
I've got a yellow triangle on my screen and when I've made a diastolic it said me next fault:"Ambient air temperature sensor 1 circuit-voltage above normal or shorted to high source.High signal detected at ambient air temperature circuit."
I went to 3 dealers.And all of them keep telling me different sensors I need to change.
On the last dealer we checked under the radiator,inside of the driver mirror and by the fifth wheel and didn't find any sensor.But on the diagram it shows that I need to change some other sensor by the ECM.
Could someone help me please.
In the end I don't even know what I am looking for and where it should be.
Thank you a lot.

[Waterloo]

Well, the temp sensor was wrapped in the wiring harness on the driver side by the hood hinge on my 2008 ProStar, under the radiator. There was a bulge in the electrical tape, that is how I found it, and it was not easy. I had been looking for that thing for over two years. Oh, the dealer told me mine was mounted in the mirror housing too.

If that is your problem, I really can't tell you, but it is a place to start. Find it in that harness, dig it out and run the wire. Check for breaks or bare wire.

Here is a link to Navistar Bodybuilder, http://bodybuilder.navistar.com/General/...s08339.pdf it has all of the electrical nonsense on your truck. I would start at the temp sensor on the schematics and work your way back to the ECM. I am sure it runs through any number of sensors and other nonsensical places. Like the compass module that my ABS brake system and Jake run through. I am sure it is the same with that Ambient Temp Sensor. I believe that is why you are getting so many answers as to what to replace. The schematics are your new friend. ;-) Good luck!

[Ross Bezvy]

Thank you a lot.
Now at least I have an idea which way to move.
Will check it.

[Waterloo]

I found my issue by taking the truck in and having the tech run Diamond logic on the cab controller. It simply said "compass module". I then had a starting point and ran the wiring via the schematics and discovered that the ABS and Jake ran through the compass module. The dealer wanted $345 for one, and they were not available, not that I would have paid that ridiculous price! I went on eBay and found a NIB one for $20.00. I bought it not knowing 100% if that would fix my issue, but for $20 it was worth a shot and it did fix my issue. Hell, I had no clue the truck had a compass, as it never worked! Now I have a compass, that reads N when I am heading SE, but oh well, the idiot lights are now off and no more codes. International sucks. LOL!

[Hedley]

On a 09 prostar is should be under your fifthwheel grounded to the chassis. the sensor is PN# 4009860

[Ross Bezvy]

Thank you for your help.

[Muchos189]

I had the same fault come up on my 2011 and I found that ambient air temp sensor to be located directly under the radiator.

[kmk]

For anyone having issues with a/c. My truck is an 09 prostar, an old revision bcm software. Long story short the bcm was cutting power off to the compressor randomly at first then completely, after initial start up. There was nothing wrong with the system at all. The ambient temp sensor was stuck high due to corrosion at the plug. The software in my bcm compares the temp reading with static pressure from the transducer and decides whether the system is low or high on refrigerant. I never thought this was the issue. After fixing it its been running for nealy 2 months without issues. I wish International would provide more info on their programming and the different revisions. Talked to a tech that works for them, he wasnt aware of it, yet he confirmed my suspicion on a few other trucks including straight trucks later. Its beyond me why they dont provide info to their dealer network on how their software works. So if anyone has erratic ambient temp reading fix it. Its an important sensor.

[Waterloo]

(07-30-2017 )kmk Wrote:  For anyone having issues with a/c. My truck is an 09 prostar, an old revision bcm software. Long story short the bcm was cutting power off to the compressor randomly at first then completely, after initial start up. There was nothing wrong with the system at all. The ambient temp sensor was stuck high due to corrosion at the plug. The software in my bcm compares the temp reading with static pressure from the transducer and decides whether the system is low or high on refrigerant. I never thought this was the issue. After fixing it its been running for nealy 2 months without issues. I wish International would provide more info on their programming and the different revisions. Talked to a tech that works for them, he wasnt aware of it, yet he confirmed my suspicion on a few other trucks including straight trucks later. Its beyond me why they dont provide info to their dealer network on how their software works. So if anyone has erratic ambient temp reading fix it. Its an important sensor.

That makes perfect sense! I am one of the many poor slobs on here that has fought AC issues for more than a few years on my 2008 ProStar. I would think I had it working and then right back to nothing, no AC. It was driving me nuts. Well, one day two or so months ago, more AC issues. I went and dug out that ambient air temp sensor from under my radiator. I ran the wiring and pulled the two wires out right up to the firewall. I remounted the air temp sensor up on the cowl at the driver side hood area above the door hinge. This did not solve the problem, yet.

I tore the dash apart, pulled all of the AC system out, inspected everything with a multimeter and power probe. I discovered the new HVAC control unit I had installed last year was not sending a signal to my upper blend door actuator. I drove the truck in pieces up to the dealer, exchanged the HVAC control for another, it was warrantied and installed. Well, still not working. I asked one of the techs to check with his laptop. He did a reset on the blend door, that is what he said. Whatever he did, the reset, solved the issue I came in with. I left there with ICE COLD AC! That was well over a month ago and it is still blowing ICE COLD.

The one variable here, having been through this process many many times, was that I moved the ambient air temp sensor out into the open. Whatever Ethan did at the shop was incidental. Getting that air temp sensor out from under the radiator, at least I believe, solved my issues. And that sensor, in its factory location, wrapped in tape and stuffed under the radiator was reading all over the map. Now, it is within reason and I suddenly have AC.