Three things caught my attention yesterday while driving about; they most likely all occurred at the same time, but I felt and saw them in this order. The OD activated, the tow/haul light flashed, and the trans temperature gauge plummeted to a low point missing signal. I looked underneath the truck first. Nothing seeps out. Trans fluid came in second. Complete and spotless.
I assume the trans temperature sensor had a breakdown? That appears to be the typical response for these symptoms based on what I’ve seen on a few boards.
But as of right now, everything is good. I ran my errands, and the temperature returned to normal. Once it was dead, I would have thought it was dead. Does anyone know anything about this?
It is a common issue, usually works fine when cold but starts acting up when it gets hot. I recommend buying the part directly from Ford since it is affordable and you avoid the risk of getting a non-factory part. Make sure to also get a new pan gasket, filter, and 6-8 quarts of Mercon SP if possible. While Mercon SP has been replaced by LV, SP tends to stay cleaner longer. I have saved a couple of cases for my 6.0.
Mine would read correctly when it failed up until it hit a specific temperature. I would estimate that it was between 150 and 160 F, after that, it would fall out of scale.
Before replacing parts, try using Forscan or a similar scan tool to run diagnostics. The issue might be in the wiring harness, which replacing parts won’t fix.
Yes, however replacing a TFT sensor is inexpensive and a frequent issue. If there is a bad wire, I would prefer to identify it first and replace the fluid, filter, and sensor.