Ambient Air Temperature issue
 

Hey all,

I have a 2014 Ram 1500 Big Horn, non-tow package. A few months ago my outside air temp read -40 and has been stuck like that.

I started combing forums for the sensor locations, images, wiring diagrams and generally speaking its "in the drivers mirror behind a panel you pop off". On the mirrors on this truck, there is a small circular panel I can pop off but nothing matching photos on the internet of other peoples mirrors with a sensor tip hanging out.

Inside the small circular panel I noticed a green and a purple wire that seemingly were soldered together but broke due to rust. Once I reconnected these wires, i noticed the outside temp went to 185, implying that these wires have something to do with that circuit.

What are these wires? AND where is my sensor so I can swap that out while I'm in here.


https://cimg7.ibsrv.net/gimg/dodgefo...07a44caad1.jpg
Inside of the driver mirror
https://cimg3.ibsrv.net/gimg/dodgefo...bb28dafd3f.jpg
Sensor I purchased
https://cimg5.ibsrv.net/gimg/dodgefo...d393c80b95.jpg
Random wires that were seemingly soldered in the past

That little bulb at the end of the purple and green wires is the thermistor, not a solder splice. If that third image is how you found the wires and before you did anything, it would appear that a previous owner may have soldered in a thermistor and bypassed the connector, or maybe aftermarket mirrors were installed that don't use the same part as the OEM mirrors. Based on the rusty screw heads behind the mirror glass, I'm suspecting aftermarket mirrors.

-Rod

Rod! Thank you for the reply.

Very interesting point! I'm curious what the resistance is.. I may run out and pick a few up.. try to swap them in. Or ill just buy a new mirror hah

-Chris

If you happen to have a decade resistance box you could try adjusting resistors to see what value causes the correct reading for the outside temperature, then figure out if increasing the resistance causes the temperature reading to increase or decrease. Armed with that information you should be able to pretty easily determine what the correct thermistor value should be. Doing a quick Google search, it seems Dodge likely uses a 10kohm @ 25 degrees C NTC thermistor. You could also measure the new one you purchased to see what the resistance reads at room temperature.

If I get ambitious later I'll connect my scan tool to my 2014 Ram and see if it will tell me the actual resistance of the sensor for the outside temperature.

-Rod

For the time being I soldered in the real sensor i had purchased. I was going to buy a variety pack of the thermistors and test each one until I get it back where it should be.

I need to put some miles on the truck to see if the CEL goes away with the sensor. No clue if it'll work!

-Chris