Does the tranny temp gauge on these trucks provide any real info, or is it basically an idiot light? After starting the truck, mine is all the way on the cold side of the gauge and climbs slowly to almost the midpoint, but never moves after that. It doesn't matter whether it's cold outside or hot, city or highway driving, towing 10k lbs or empty, it always just stays in the same place. That doesn't seem right to me.

 

I have thought the same thing about mine and I think its more of and idiot light than anything else. I watched mine last year when I was towing our fifth wheel up a steep grade it never moved and it was about 75* that day. I am trying to talk my wife into letting me get at set of guages for the truck so I dont destroy a tranny or turbo.

 

Yep. Last weekend in 80* weather, climbing hills on the interstate directly into a ~20mph wind with my horse trailer loaded down for a weekend it never moved. I think I'll end up with a ScanGauge since I don't need to monitor boost pressure or EGT.

 

I have thought about the Scanguage as well but I may end up with a set of ISSPRO guages or Edges digital guage.

Edit: I have also heard that the temp reading depends an where you have it located in the transmission.

 

AS long as the cooler is clean and unblocked your trans shouldn't heat up enough for the gauge to move, once it is at tempurature unless there are internal or electrical problems (bad sensor, low fluid, mechanical failures, etc.) it shouldn't heat up towing. If your stuck in the mud or doing a very intense tow up a long hill then it will heat some but not a significant amount.

They are not dummy lights like the engine oil pressure lights are lol its built into the valve body in the front corner of the transmission pan.

 

I find it hard to believe when I am towing an 11k fifth wheel up a grade on a fairly warm day that it wont heat up the transmission. I dont have guages yet but buy the time I got to the top I could smell that she was getting warm and pulled over at the rest area on the other side to idle and let it cool off.

 

I understand your line of thinking, but I'll phrase it better so you understand better what I am saying:

The sensor and gauge - functional 100%.
The transmission system has 2 coolers usually from factory one in line with the radiator and the secondary being the smaller external cooler. With all the cooling system running properly what it ironically "boils" down to is that as long as you don't push your motor to the point it overheats or heats up, the transmission itself will not experience the type of tempuratures that will cause damage or issues.

Just thought I should clarify better, and as for the pulling over to cool down... ambient heat spreads more when you sit than if you were doing 50-60mph on the highway, its one of those old urban myth/wifes tales of the truck world.


This is the location of your transmission tempurature sensor/switch that controls the gauge on your dash, just so you know where it is (front passenger corner of the valve body between two shift selonoids)

 

The 08 has an external tranny filter and cooler. The transmission does not circulate the fluid through the filter and cooler until the fluid reaches operating temperature. This is why the truck will not shift into overdrive on a cold morning until the tranny temp comes up to a certain point. This is one reason that it is bad to make very short runs with the truck on cold mornings. If you don't get the tranny up to temp, then you are not filtering your transmission fluid at all. When I drive home from work on cold mornings, I know exactly what point along the way my truck shifts into 5th gear. the distance gets shorter and shorter as the days get warmer.

 

I know this sounds like a stupid question but where is the Transmission temp gauge? I did not think any of the gauges on the cluster were for the transmission.

 

The upper right one with the gear is the trans temp gauge.

 

Yup I got one. It is in a different place but it is there. Had the truck 6 days and never noticed it was a transmission temp gauge. Good thing I did not have one installed.

 

You don't need to install any sensors on the 08+ Super Duty trucks. They have all the sensors installed from the factory. It makes it really easy to add the gauges that you want.