transmission temp reading "zero" at 32 degrees..

[JThiessen]

I have a quadzilla commander in my 06, installed per quads instructions. transmission temps have read what I thought were normal readings until the temps started falling to below 40 degrees (I live in the greater seattle area). Every now and then I'd notice that the readings were about 115-120. Then on Xmas day we drove to Montana, and temps were right at 31 - 33 dgrees F, and all the way my transmission temp read 104 (meaning it was at the default or zero reading). Does this indicate that my sender is bad? I'm going to put it up on the lift tomorrow to check it out, and would like to know what to look for in advance. Thanks!



Someone mentioned that my TC may be locked up, thus not getting the oil hot, and thus my readings being low. How can I check this, and what other so called symptoms of the TC being locked would there be? I have a Jake brake and drove the first 500 miles with it on, then the last with it off, but that didnt seem to make any difference in the reading.

 

[GECCO]

At highway speeds your torque converter is locked up. This is not a problem, this is what it is designed to do. As you pull away from a dead stop to highway speeds you should feel 3 shifts and then see/feel the RPMs drop again after you are in 4th gear, almost like an additional shift. This last one is the TC locking up.



The TC is basically a torque multiplying device when it is in it's unlocked mode, sort of like driving a manual transmission vehicle with one foot on the clutch, allowing it to slip a little bit. Heat is a natural and unavoidable byproduct of any process that "creates" energy (as you are doing when you multiply torque). This heat goes into the transmission fluid, and is the reason behind the need for a transmission cooler.



However, at highway speeds there is no need for torque multiplication (since it takes much less energy to KEEP a vehicle moving at a constant speed compared to what it takes to accelerate it to that same speed). Imagine you had a manual transmission vehicle and you were only allowed to use top gear. In order to get it to highway speeds you would multiply torque by slipping the clutch (a lot) until you reached highway speeds. But eventually it would no longer be necessary, and after that point it would be foolish to drive down the highway slipping the clutch, right? Not only are you wasting fuel, but the clutch wouldn't last long.



So, at highway speeds the TC locks up and lowers RPM's which makes for better fuel mileage and less abuse of the transmission fluid.



The "problem" you are seeing is a result of the fact that driving at highway speeds is the circumstances under which there is the least amount of heat being put into the transmission fluid, and the most amount being removed from it via the large amount of air flowing over the transmission cooler. Add in the cold temps and the effect is greater.



I don't see it as being a tremendous issue, but all you have to do to solve it, if you wish, is to block some or all of the air from flowing through the transmission cooler/radiator. There are lots of "cold weather kits" that do just this, or you can simply zip tie a piece of cardboard across it.