That is precisely what I was wondering about the past few days due to the JK 42RLE recall that enables the display to show "Hot Oil" when the tranny overheats.

Thanks for your testing.

I've got this to install after I verify it can get a reading from the trans sensor...

But I can't figure out the best place to install it in this...

Mine doesn't have power windows, so the area between the two center air vents is available, but I've got to get out there tomorrow afternoon and measure and see if my gauge will fit between them. What do you think?

 

My Snap-On Modis also displays the trans temp.
The voltages vs.temps are listed on the Snap-On Shop Key, problem is finding a compatible aftermarket gauge to tap into it with..
that is something unlimited04 had been researching as well.

 

the snap-on thing may be accurate, especially if you're plugging it into the OBDII port. My ScanGauge isn't able to read trans temp, and I've sent some info to ScanGauge (the company) and they are supposedly working on getting the XGauge protocol to read trans temp....but no timeline. With OBDII, you need to know what protocol to use to get into the TCM...since trans temp is stored in the TCM, NOT the PCM. Noone that I know of has been able to crack that...besides the StarSCAN at the Chrysler dealership.

Maybe Snap-On has, or is using StarSCAN protocol or something. I wouldn't be surprised if Snap-On leased the technology from Chrysler or something along those lines.

The problem with using an aftermarket gauge is they don't work on the same temperature-voltage specs. The stock sensor is a dual range trans temp sensor, so basically you need digital handling to deal with the non-linearity:

To add an aftermarket trans temp gauge & sensor usually requires cutting into the hard trans lines, means you need to flare them....unless you use this: http://www.jeepforum.com/forum/f130/no-modification-auto-trans-temp-sensor-adapter-977088/

Check out jeep2008's gauge :shhh:
http://www.jeepforum.com/forum/f9/my-jeep-pics-my-little-mods-so-far-584434/index19.html#post8632152

 

The gauge is as accurate as can be

http://www.jeepforum.com/forum/f9/my-jeep-pics-my-little-mods-so-far-584434/index19.html#post8632152

 

Unlimited04 decided to pee in my cheerios today... :laugh:

If a person was on the fence trying to decide to add an aftermarket B&M fan cooled trans cooler to the 42RLE, the OEM trans temp sensor issue would prompt them to go ahead with the aftermarket cooler and plumb an aftermarket temp sensor in with the B&M to run the AutoMeter gauge wouldn't it? :ballchain:

 

well the way the trans lines are connected to the radiator & stupid plastic fittings makes a cooler a pain in the butt. on a TJ, there are no NPT fittings you can just thread in or out...i'm sure a JK is similar. so you end up cutting the soft line and splicing in the trans cooler. there are arguments for doing it on both the return side or inlet side of the radiator. i'd go return side...the 42RLE runs hot in extended mixed city/highway according to my gauge (190*F+), and very close to "Overheat mode" in the mountains, and if you're towing it would certainly be over 220-240*F, maybe even into "Super Overheat Mode" :brickwall.

thats why a sensor that doesn't cut into the hard lines is nice...less plumbing and less BS, plus still accurate enough.

 

Today i went in an off road trip with a couple of my friends.The Jeep was, for the 5 hours duration of this ride,half the time in 2H and half the time in 4H.But we were moving really slow cause the trail ride was new and really narrow.Anyway shortly after we started i had my trans at the 2 or sometimes the 1 position and the gauge showed this



After half an hour it went there



It stayed there all the time we were moving slow and only when we drove in dry roads for 12-15 minutes, between trails ,a little faster than the 5-10 miles we were moving all day, it came a little down.Also when we stopped for half an hour for a brake it really cooled down but for the rest of the day it was that high.Any thoughts?

 

Any thoughts?

was the sensor wet from snow or mud? was the needle bouncing?

if no to both...then its time for a transmission cooler...you were definitely in "Overheat Mode" at those temps....did you notice any difference in shifting?

 

 

In the grill for me, but what's the best way to mount the cooler:

Side ways, fitting side down or fitting side up (fluid would drain down first)?

 

In the grill for me, but what's the best way to mount the cooler:

Side ways, fitting side down or fitting side up (fluid would drain down first)?

I would let fluid line routing dictate the direction I mounted it. I think it'll be easiest that way. Since it's a pressurized line, the direction of the fittings should not matter.

 

I just changed the fluid in my tranny. While I had the pan out I drilled it and put in a Summit drain plug kit for about $6 bucks. It had an 1/8" npt thread for the plug. I bought an Auto Meter trans temp gauge and screwed the sending unit into the drain plug bung. It works great. Reads about 130 degrees in stop and go traffic. It took all of about an hour start to finish. I know a lot of guys like to run the sending unit in the cooler line but the pan was good enough for me and it seems to be pretty accurate.

I have a B&M cooler and remote filter kit. As soon as I install it I'll post a write up. Still haven't decided where to mount everything.

 

I just changed the fluid in my tranny. While I had the pan out I drilled it and put in a Summit drain plug kit for about $6 bucks. It had an 1/8" npt thread for the plug. I bought an Auto Meter trans temp gauge and screwed the sending unit into the drain plug bung. It works great. Reads about 130 degrees in stop and go traffic. It took all of about an hour start to finish. I know a lot of guys like to run the sending unit in the cooler line but the pan was good enough for me and it seems to be pretty accurate.

Good thinking! Next time I drop my pan I was going to put in a drain plug too. Thhis just gives me another reason to do it sooner. I already have a sensor in the cooler lines but was thinking of a Bransford dual sensor setup, with a switch to go back and forth.

 

Tranny Temp Guage

Great thread peoples! So I bought a transmission temperature gauge and an air pressure gauge for my york compressor. The instructions I found online recommend either replace the factory sensor with the sensor provided (unless the sensor is connected to the PCM which it sounds like for an 04 TJ rubicon) or use one of the test ports. Any thoughts?

 

The instructions I found online recommend either replace the factory sensor with the sensor provided (unless the sensor is connected to the PCM which it sounds like for an 04 TJ rubicon) or use one of the test ports. Any thoughts?

the factory temp sensor is mounted to the valve body and cannot be replaced with anything aftermarket since it's integrated into the computer. you can't run your aftermarket gauge off the factory sensor either since the factory sensor is a two stage sensor.

best idea is to plumb the transmission temp gauge into the inlet from the radiator back to the tranny (cold side), or into the outlet from the transmission (hot side), or TIG weld a sensor bung into the transmission pan.