Mine does it randomly. I moved a total of 16,000lbs of rock and soil over a couple days, nothing. Next day on the way home from the aggregate yard (empty), light comes on as I pull into my driveway. It was on for maaaybe 2 Mississippi's, and then went out on its own.

Fortunately since I was home, I had my scan tool hooked up immediately. It showed a consistent 79ēC (manual suggests 79-85 is normal). Went for a little rip around the block with the Autel plugged in, and it stayed at 79ēC. I did however, notice that the voltage from the sensor was alllllllll over the place, though the temperature never changed. Voltage would be at 2.88V (consistent with temperature), and suddenly drop off to 0.15V, and instantly back to 2.88 or thereabouts. 5V signal remained unchanged, so the culprit is likely a bad connection somewhere.

 

I was doing some work on the truck this spring and thought about this. I disconnected the big electrical plug on the transmission, cleaned both parts with contact cleaner and slathered it with "bulb grease" (silicone grease) and the temp sensor alarm hasn't come back in since then (so far...,)

 

Just doing a few things to the truck. Since it's up on jack stands, I took the trans connector off. Both sides looked fine, but I cleaned and greased em anyway. Then I took off the C4 connector at the PCM, and the pin on the PCM had some scmutz on it. Compressor couldn't blow it off. Used contact cleaner, and that took it off. Hit it with di-electric. We'll see how it goes once it's back on the road.

 

My 05 Dakota did the same thing and here's what fixed it. I had 5/16th hose on 3/8th hard lines from the tranny. Tubing (metal) is measured on the OD. Hose measured on the ID. I put 3/8th hose to the tranny cooler. More flow in and out. It's never repeated.

 

I've unplugged the harness connector on the transmission and cleaned it with electrical contact cleaner and stopped it for a few months, but it always comes back. If you scan it gives an "implausible temperature", not high temperature. That's caused by a loose connection giving negative temp readings.

 

Ive been battling this for a week now. Flushed radiator, new thermostat, next move was the sensor but I'm reading alot about connectors and now flow. Is there a way to test the sensor?

Truck studders at 40 mph, temp slowly rises, sometimes cools off by itself, randomness