The temperature guage I have is digital that starts reading at 72 degrees. Below that temp it blinks 'LO'. I have been getting fluctuations in temp reading as if there may be a thermostatic temp bypass in the cooling system for the trans or I have a sending unit that is goofy. I had the trans flushed and filter changed then had the trans temp guage installed. The trans is starting to heat up faster now at these temps than it ever has since I had the guage installed. I get up to about 125 and suddenly it's reading below 70 then it climbs back up to 125 and stays there for the most. Any ideas?

 

Sounds like you indeed have a goofy sending unit.I cant think of anything that would create such a sudden reading change.My first thought would be restricted tranny cooler,but if im reading the post correctly,a restricted cooler would just let the temp climb,and keep it there.....

 

What make and model of gauge do you have? It sounds like a sensor problem. Did you use teflon tape when installing the sensor? Some sensors need a good ground path. I've been working on installing a trans temp gauge on my '08. The first gauge I chose is a Autometer Carbon Fiber. However the Fiber face doesn't come anywhere close to matching the carbon fiber trim of the truck. So I decided to get a MSD Superchips Lazer gauge. It arrived today.

 

My guage is a digital one. It's what came with the package. My trans shop sells/installs them. The sender is in a holder of choice the shop owner has made. It is directly in the path of fluid from the trans so as to give a more accurate reading. This problem, if it is one, just started recently. Oh that lazer guage is nice and it starts reading at 50. I want one of those babies.