kpadawe Posted July 5, 2017 Report Share Posted July 5, 2017 (edited) So, this began yesterday. After a short drive around town, pulled the car into our garage and stopped the engine. Fan was still running as is normal on shutdown. Hour later, the fan is still running on high. Opened the hood and the upper radiator fan running loud enough my wife insisted the car was still running. It was not. The temp gauge never went above the halfway mark while we were out. So, wondering if it there was a gauge issue, I started the car and turn on the heat MAX fan and temp and lowered all the windows. Let it run for 20-30 minutes and then shut down. engine and fan ran continuously until I unplugged it. The car has been sitting in my garage over 14 hours now and the overnight low was 67 degrees. Popped the hood and plugged in the fan, it energized and went to high before I could snap it in. I am thinking temp sending unit has to be the culprit. There are no warning lights or check engine lights. Still, it is possible the system firmware needs to be flashed for a firmware issue. Does anyone have experience with this behavior? Edited July 5, 2017 by kpadawe Quote Link to comment Share on other sites More sharing options...
akirby Posted July 5, 2017 Report Share Posted July 5, 2017 Could also be the fan controller. That was a common failure on the early models although the failure mode was typically not turning on one or both fans. When you restarted it after letting it sit for a few hours, where was the temp gauge? If it immediately went to normal I'd say it's the temp sensor. If it started on cold then it may be the fan controller. 1 Quote Link to comment Share on other sites More sharing options...
kpadawe Posted July 5, 2017 Author Report Share Posted July 5, 2017 (edited) Temp gauge was right across the water level mark on the display, just below the mid point, the entire thermometer graphic was visible. Man I prefer numbers over pictures. I ran over to the local Ford Dealer, they cannot look at it until Monday so I figure I get to do the repair., And to your point, the lower fan is not or does not appear to be affected, it seems to turn off as designed. I have a camera, like a borescope, that I will use and confirm the fan is spinning while the car is running. So I went and started the car with the upper fan unplugged and the lower fan was not spinning. I plugged in the upper fan and the lower fan also started. I then unplugged the upper fan to confirm the lower fan also stopped. that is the limit of my diagnostics at this time. Oh Coolant level is normal and I did top it off with the correct specification, WSS-M97B44-D2, of Orange 50/50 pre-dilute when this began yesterday. Edited July 5, 2017 by kpadawe Quote Link to comment Share on other sites More sharing options...
akirby Posted July 5, 2017 Report Share Posted July 5, 2017 That would lead me back to the fan controller as the most likely culprit which you can replace yourself. Make sure to use OEM parts though not Dorman or the other aftermarket supplier whose name escapes me - lots of problems with those. The controller comes with the fans. 1 Quote Link to comment Share on other sites More sharing options...
kpadawe Posted July 5, 2017 Author Report Share Posted July 5, 2017 (edited) thank you!. and yes, I have mixed experience with the aftermarket brands on my truck. I have a 200 Tundra I bought new in 99 and the few times I have tried aftermarket, it has stung me. I will pick one up and update the thread on success/failure. Edited July 5, 2017 by kpadawe 1 Quote Link to comment Share on other sites More sharing options...
IWRBB Posted July 5, 2017 Report Share Posted July 5, 2017 It should never run with the vehicle off, no matter what the coolant temps are. It has to be an electrical issue with the power feed to the fan. 1 Quote Link to comment Share on other sites More sharing options...
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