Ambient Air Temperature Issue

[sheltonfilms]

This is for the evap temp sensor but should be the same for the ambient:

Ambient Temperature Resistance
-40° C (-40° F) 832,519-1,017,523 ohms
-20° C (-4° F) 263,111-290,807 ohms
0° C (32° F) 91,058-100,644 ohms
20° C (68° F) 35,473-39,207 ohms
25° C (77° F) 28,500-31,500 ohms
40° C (104° F) 15,307-16,919 ohms
60° C (140° F) 7,171-7,925 ohms
100° C (212° F) 1,976-2,184 ohms
120° C (248° F) 1,131-1,251 ohms

 

[finally03gt]

I got busy last night and didn't get to it. I'll try again tonight maybe.

Seems pretty straight forward. Higher sensor resistance decreases Ramb and visa versa. I guess that's where the reset process comes in. My first thought when it still didn't function was that it was a scaling issue in the digital to temp conversion, but that's because my equipment is scalable. I guess this is on a fixed data table for temps.

I tried to read resistance on the sensor but got OL each time. But.... my meter isn't the highest quality, and I honestly didn't realize the resistance values where that high, so I may need to select a different range and try again.

I don't have any resistors. My neighbor is building a floating radio and I asked him, but no luck. Man I would love to have an Ohm Ranger like we had at work. And a good meter. Frustrating to be handcuffed at home by lack of reference material and equipment.

I'm going to start with double checking my pins (not really looking for full 5V, just making sure voltage and ground are on the correct pins), then the reset, then driving it. If I turn up empty there, I'll try to dig into resistance readings.

Post 16 in this thread had some cool info on PCM logic for this circuit. That's where I got the idea to try driving it.

Thanks for all the insight. Forums (most of them) are awesome!

 

[finally03gt]

Polarity was right. Reset process didn't change readout at first. Then I went for a drive, and sure enough, every 30-60 seconds it would climb 2-3 degrees. When I hit the highway, after about 90 seconds, it started to climb rapidly, until it leveled out at a believable temp. Thanks for everything guys, I never woulda figured that one out alone.

 

[EdgarSanchez]

Hi Forum, Can someone help me confirm that my 2018 Ford Explorer has the same wiring scheme as the 2012? My explorer was hit in the front left, had front radiator support, bumper, grill, etc replaced including repairing damaged wiring. I can't figure out exactly where the sensor goes as well as the wiring the comes to it. If it is same as on link on this thread, I will start tracing wires coming off the junction box. Yellow/GN Pin 1 and Yellow/Violet Pin 2.

 

[EdgarSanchez]

picture of what I'm working with.