Transmission Temperature sensor location

[cncsparky]

For those wishing to add a transmission temperature gauge, there seems to be at least two prevalent places to install the sensor.  The transmission pan or the supply/pressure line to the cooler.  I was not able to come up with much information as far as the best location to use on the web(other than personal opinions  ), so I emailed around 6 transmission shops to ask them their thoughts.  Here are the responses in the order I received them. ( only got 4 responses). 

Question:  What is the best location for a transmission temperature sensor for a TH400 in an RV application?

1.  From Jakes performance transmissions. http://jakesperformance.com  "Go into the pan, it's the best avg temp."

2.  Hughe's Performance  www.hughesperformance.com   
"Thank you for submitting a contact form with Hughes Performance.  We recommend installing the sending unit in the transmission pan.  This is the most relevant fluid temperature reading you can get from an automatic transmission.  If you have any other questions or concerns, please feel free to contact me at any time.  Thank you for your interest in Hughes Performance!"

3.  TCI transmissions technical support.  www.tciauto.com 
"Sorry for the delay.  But all the sensors will need to be in the pan."

4.  Chance transmissions  www.chancetrans.com  "Hi, either the pan or the trans cooler line; pressure side.  Cooler line is preferred but requires a kit with all the goodies to do the job.  We carry it in a B&M kit for $85."

[LJ-TJ]

  Well done mate. Good solid information. Thanks.

[plockit007]

Hello and thanks so much for the tip...in the pan sounds the most logical way to go. I had my Tranny rebuilt at Aamco. So I will check with tem and see whats up.  Enjoy the rest of your year and wishing you a Happy and Healthy one.

[TerryH]

Thanks cncsparky.
This is and has been a contentious issue.
Your checking with various AT shops helps a lot.
Terry

[Froggy1936]

I beleive that the pan is the best location. That is where the workings of the trans gets the fluid from through the filter.  The temp at the pressure line is after the fluid has done its work and is leaving the trans for the cooler (this will always be a higher temp reading ) But you cannot do anything to change it . The temp at the pan is controlable by cooling with additional coolers, Fans, Ribbed or vented pans, or increased pan depth for additional fluid . The use of the test port on the reverse servo will give you a reading (though it will always be low except when useing reverse for a long period of time) as the fluid at that point is usually not circulating But the case will get hot also eventually . All factory temperature pickups for computor controlled transmissions are located in the valve body wich is in the reserve fluid of the pan ! ASE Certified Master with over 50 yrs of trans repairs . Frank

[cncsparky]

Thanks guys!  I put a sensor bung in my pan and seemed the logical choice until I read about the cooler line location.  For the majority of us RV'ers, the pan is probably the best choice, verified by the above responses.  Now, if you are very technical and want/need to know the temperature spikes of the tranny, the other location might be best.  I'm just not sure what I'd do with that information  i?? .

Froggy, that is a great explanation 

[eXodus]

After reading all this, I would still opt for going into the transmission cooler line.
But this is my personal opinion since I'm a technical guy and want to know whats going on and not the best average temperature

I would like to see the temperature spikes.

And think about this: the transmission shops don't want a lot of calls from their costumers that their trannys gets too hot. So they pick the place where it has a nice average temperature.

Since I think the temperature spikes are the cause of transmission fluid breakdown, I want to know about them.
I can not do anything about it, yes but I can estimate when I've got a lot of spikes that I have to change my fluid earlier.

Just remembered something, I had once a car where I measure the fuel temperature at the surface of the metal line right where it leaves the transmission:
I just glued a  sensor (epoxy) to the line and wrapped some insulation around it:

http://www.amazon.com/RioRand-Digital-Thermometer-50-110%C2%B0c-Temperature/dp/B00JA9PVJC/ref=pd_sim_sbs_pc_7?ie=UTF8&refRID=0M45ECC4K6ZJBG14X112

http://www.amazon.com/DROK-Fahrenheit-Digital-Voltage-Temperature/dp/B00E7OF820/ref=pd_sim_sbs_e_1?ie=UTF8&refRID=02Q7CWZARY33WSN7V90F

[tmsnyder]

This is an old thread, I went through a similar exercise but came away with a different conclusion.    I chose to put mine in the return line from the cooler to the tranny b/c  I want to see that the cooler is doing its job.  And it defines the upper limit of how hot the pan fluid could possibly be.  As long as it's in an ok range on the return, then I know the pan temperature is fine.

[Sasquatch]

Mine was in the return line, i.e. cool side for many years.  It is now in the hot side of the cooler line.  The cool side had issues.  It could not see any temperature spikes, and quite honestly, stayed pretty stable.  Now that it is in the hot side I can see how the transmission temperature changes with driving style and loads.  I am having to recalibrate my mind to what temps are good, but I like seeing the temp changes.  I know the coolers are working by watching the temps fall after working it hard climbing a hill and going down the other side.  By having it on the hot side I can shut her down if temps get near the maximum allowed for transmission fluid, where when it was on the cool side I never knew what temps the transmission was really at.

[fasteddie313]

If you are undecided you can run more than one temp gauge and sensor, or just multiple sensors and a toggle switch to a single gauge to switch viewing between sensors.. 

[Froggy1936]

I have a toggle switch with one sensor on the rear of the pan and the other in the radiator at the oil cooler area ! There is a massive difference in temps !  Frank