I am looking for some information about the transmission bypass valve on the 2012+ JK's. I added a temp gauge to the line going to an aftermarket cooler, but it is after the bypass valve. My gauge does not read anything which makes me think the bypass valve is temperature controlled? I have an extra in my garage because I boogered up the threads replacing one of the lines, and it all looks mechanical with springs with nothing that looks like a thermocouple.

Can I get some insight on how this valve works? I'm wondering if I need to move this temp sensor pre-valve.

 

Is your cooler the OEM one in front of the radiator and A/C condenser that comes on the 2012+ JKs, or is it an actual additional aftermarket cooler?

The valve you took apart is probably a pressure bypass valve to protect against cooler blockage.
If that's the case, seems like it would have 3 lines connected to it.

 

We use to put trans temp gauge sending units in the trans oil pan.

 

Pressure bypass for blocked cooler makes sense. It has 4 lines coming from it. If you look at this image it is number 7.



If that's the case, then I don't understand why I would not be registering a reading unless my fluid is just staying <100 degrees which I doubt.

Maybe I have a bad connection or something.

 

Would you protect it with a skid plate of some kind? Sounds like a good way to rip a hole in your pan if it gets hung on something. Also, wouldn't that be a false reading since it had already been through the cooler as opposed to checking it at the outlet and monitoring its temp as it heads to the cooler?

 

Not a false reading. You want to know the temp of the fluid the transmission picks up in the sump to circulate. The temperature of the fluid on its way to the cooler can vary and be relatively high, depending on what the torque converter is doing.
The onboard computer's temp sensor is exposed to sump fluid. That's the temperature the computer uses to make decisions.

It's when the sump fluid temperature begins to rise that you know the transmission is making more heat than the cooler can get rid of.

See post #17 in this thread: https://www.jk-forum.com/forums/modi...-sensor-39769/

 

I can see how that would make sense. I've always been under the impression that you would want to know what was going on inside the case as a true indicator if something was going on and the best place for that would have been on its way to the cooler.

Thanks for showing me this.

Looks like I have a line to fix and a hole to drill.

 

It would certainly be worthwhile looking for a spot off the ends of the trans pan where it will naturally have more protection. In the case of the 08 with 3.8 the front of the pan is protected by the trans crossmember.

 

I put the sensor on the side, and installed a drain plug where it is designed to have one.