fahrout

Hi, Folks:

My son-in-law has a 2007 Grand Cherokee (V8, I think) that's been out of commission for several months. When I ask him about it over the weekend he said that he was told that the problem is some kind of temperature sensor that is located on the top of the transmission. If the sensor puts out a high temperature signal, the transmission is forced to shift down to 1st gear (?). Unfortunately, he's been told by two dealerships and the usual outlets (O'Reilly, AutoZone, etc.) that there is a 2-2 1/2 YEAR waiting list for that part and that this situation has something to do with some kind of recall from several years ago?

I kinda got into this second hand but he's a good kid and I'd like to help him out. If any of you folks have experience with such a thing, know what the part is called or what part number I need or have any suggestions on where I might find such a thing (including salvage yards), I would be forever grateful.

Thanks so much!

dave1123

Okay, the 2007 has a different transmission in it than the one in my 2000, but my temp sensor is mounted on the bottom of the solenoid pack just about the filter and is immersed in the fluid. When the fluid reaches 240*F, it sets a "Trans Overheat" light on the dash and forces it to shift out of overdrive. the temperature sensor is a simple thermistor (temperature variable resistor) and if you can find it, can be replaced with a regular 1 megohm resistor (1000 ohms) and that will tell the trans module the fluid temp is about 180*F. That should work until you get the right part. Just my opinion.

Check out wkjeeps.com for the 2007 transmission specs.

fahrout

Thanks so much, dave1123! I've learned a bunch, including the fact that a "tran over temp" message could be caused by about a hundred other things besides a hot transmission and that nobody from Mopar on down can even find what I'm talking about. Very weird. But you came through and I appreciate it. Thanks again!

dave1123

Yeah, I had an overtemp light come on for no reason myself and I stopped, got out, and pulled the dipstick to check the fluid. It was full and not too hot to hold, so I knew it wasn't really overheated. I shut the engine off and restarted. Light went off and I haven't seen it again. Go figure.

My 2000 WJ is in the shop getting a new (rebuilt) engine AND transmission! It's got 253K miles on it, but the body is still pristine so it's worth it. I won't buy anything newer because the electronics are way more complicated. This one I can still work on myself. Problem is the wiring is getting funky. 2 years ago, the rear axle blew up and took out the transfer case as well. I put good low mileage used ones in it so I'm already too deep into this jeep to get rid of it. The best investment I made was buying the Factory Service Manual from pacificcoastmanuals.com

I recently bought a 2000 XJ as a back-up and I'm really getting into driving it! It's got some issues but the powertrain is perfect.

fahrout

Thanks again, Dave!

I also got a suggestion from my local O'reilly store here in Denver to contact the Whatever It Takes transmission store to see if they can shed some light on this phantom part. Onward & upward...

Best wishes on your WJ efforts and your new XJ baby!

dave1123

If I can get this right, here's a picture of the temp sensor in my 42re in my WJ. It might help as a reference to help find yours. On the solenoid pack, in between the convertor clutch and the overdrive solenoids, there is a thing sticking up that's circled in red. That's the temp sensor. It's not available separately but comes with the solenoid pack. What I'm saying is you can clip the 2 wires and solder in a 1 meg resistor. It should work. What have you got to lose?

fahrout

Wow! This is awesome! Sorry it took so long for me to respond. Your efforts with this diagram answered a lot of questions not only for me but for the people I've been directing my questions to. No wonder no one could find a temp sensor all by itself. Again, much obliged from both me and my son-in law! You definitely went above and beyond...

dave1123

Yeah, I'm an old fart but like to "pass it down" as the saying goes. I am a journeyman toolmaker and have taught 4 apprentices in my career. Being retired doesn't stop the learning.

97grand4.0

Dave I think you're pointing out the wrong location of that temp sensor. What you have circled there is actually a plug in connector, .on the overdrive and lockup solenoids. .it's a small white plastic 2 wire thing. That actually plugs onto something contained in the transmission.

If I'm not mistaken, the temp sensor on the RE is contained in the gov pressure sensor.

dave1123

When I bought the solenoid pack, I was told the temp sensor came contained within it and you couldn't buy it separately. I never unwrapped it before I handed it to my mechanic, so I'm just going by where I suspect it to be. If not, my bad. It has to be submerged in the fluid in the pan. This is what happens when they won't let you underneath the car while it's on the lift because of insurance reasons. My mechanic had a visit from his agent and was scolded for having customers sitting on stools in the bay. He used to let me stick my nose into what he was doing, but not anymore. Hell, I helped him put the head on it!

97grand4.0

Correct, I think all three replaceables are submerged. At one time I also believed the thermistor was on the solenoid pack you indicate (clutch converter and TC lockup) I think I had read that. So I admit I'm not sure either. Have to dig more on it. But before this OP went and put in a resistor I would want to be sure.
I would add that for all my years of trouble , two weeks ago Friday I solved the major problem with the shifting in ALL gears, that being I replaced my PCM. Shifts like new. Period. Never thought possible.

dave1123

Well after they get my rebuilt tranny in my WJ, if it still shifts funny, I'll check that out.

97grand4.0

Yeah I didn't replace it for that, it was an unexpected bang for the buck, for sure.