45RFE issue

[devauxr]

I'm having an issue and I've been searching around quite a bit to try and find an answer but with no luck. I'm running into an issue where my transmission immediately goes into limp mode after replacing the input and output speed sensors.

Vehicle Info:
2003 Jeep Liberty
3.7
45RFE
180,000 Miles
3" lift kit w/ 31" tires (not sure if relevant to the transmission)

Original Issue (reason for replacing the sensors):
If I drove over an hour my jeep would go into limp mode, sometimes it would throw a code, sometimes it wouldn't. I could turn the vehicle off and then back on and everything would be fine although it would go into limp mode after a few miles. Things seemed to reset once the vehicle was sitting. I originally thought it was something to do with the temperature of the transmission and I cleaned the radiator, but the transmission never threw an overheat light on.

The fix:
After some research it looked like the transmission speed sensors were not uncommon to fail in these vehicles and would show similar symptoms. Because the sensors were cheap I figured, let's just change them and see what happens.

The new problem:
The liberty now immediately goes into limp mode and will throw a code after about a mile. The codes are P1776, and P0731 which would indicate a stuck solenoid, but that's a hell of a coincidence that it occurs immediately after changing the 2 speed sensors.

I checked the 2 speed sensors by swapping them, no issues with the speedometer, I tried swapping the old ones back in, same issue.

I was wondering if anyone out there with a little more knowledge as to how all these components worked together might have some ideas, as in, maybe there's a short somewhere, issues with the TCM or TCM Harness, perhaps a fuse.

for the record I have no issue replacing the solenoid pack, and if this didn't happen immediately (next turn of the key) after replacing those speed sensors than I would have already ordered it. This is a second vehicle that I use for work, fishing, and driving to my cabin so the wife isn't too keen on me replacing tons of parts in a diagnositc hunt if I can avoid it.

One note, I bought this thing like 5 months ago, and while I was changing the sensors I did notice newer gasket material on the pan which makes me suspect the PO had been poking around there in the not too too distant past.

Thanks to anyone who has any ideas or directions I could check out.

 

[Leeann]

What brand sensors did you install?

 

[devauxr]

Bwd, it was the only sensor the parts store had available, seemed to have ok reviews.

 

[Tog]

I thought the 45RFE was only in the CRD models

2004 3.7 limited

 

[Leeann]

^ they were in the first few months of the gassers.


I had no luck with any other brand of input/output sensors. Has to be Mopar. I had new sensors throw a code right out of the box.

 

[devauxr]

2002-2003.5 had the 45re, I think the crd had the 545re (possibly, I could be mistaken on that). I could try the mopar sensors and see where that gets me, the front sensor that pulled was definitely not Mopar though.

 

[devauxr]

I just ordered the 2 genuine Mopar speed sensors online, they should be here by Tuesday. I'll keep everyone updated. I appreciate the feedback so far.

 

[devauxr]

Mopar sensors came in, I swapped them out and no such luck, same issue. You put the jeep into drive, quick shift then she gets stuck in limp mode. Anyone else have any possible ideas? I'm not a fan of coincidence, but it seems like that solenoid really did go when I changed the speed sensors.

 

[Leeann]

It is beginning to sound like the solenoid pack really did die then.

 

[devauxr]

Yeah I'm thinking the same thing. I'm going to get the solenoid pack and swap it out and hopefully that's the fix, but man that is the most coincidental timing and seriously has me scratching my head. Oh well, weirder things have happened.

 

[devauxr]

The plot thickens.
Alright, so an update on my adventure on this thing. It turns out I don't in fact have a 45RFE, I do have a 42RLE. Now before I get skewered too much on what I would consider a rookie mistake, I must say that I did what I thought was my due diligence on identifying this transmission. The 3 things I checked to verify that we had a 45rfe

1) The date of construction: From what I was reading the switch from 45 to 42 happened in april, and anything with a date of manufacturing before april was 45. My jeep was manufactured in February.

2) TCM location, I had read that the 45 had the TCM mounted on the fender and the 42 had an integrated TCM. With a quick glance I looked at what I thought was the TCM but in retrospect probably was not. I'm not currently at my vehicle to check.

3) The cross member, I read that the 45 had a crossmember that bent towards the back and the 42 had a straight across crossmember. My crossmember 100% is not straight and has a bend to the back of the vehicle.

So now i'm scratching my head, Either I got bad info from multiple sources, or the PO swapped the transmission from a 45 to a 42 and left in the TCM and Crossmember and I suppose "Made it work". So now I've got a useless Solenoid Pack and Cam Plate for a 45rfe which I have to attempt to return.

Now back to the original issue, the 42RLE and 45RFE share the same input speed sensor but the 42RLE has a different output speed sensor which seems to have an extension on it. Does anyone think that this could be my problem or if that's 100% not feasible, should I try and get the correct solenoid pack for the 42 and just do it all. I'm leaning towards trying the speed sensor first as it would certainly explain the "coincedance" in all of this.

I'm getting a little frustrated with this issue to say the very least.

 

[Leeann]

I'd try the speed sensor first. It's cheaper and easier - you don't have to take anything apart to get to it. The solenoid pack is a bit more involved.

If yours looks like this on the driver's side

You must be registered for see images attach

And the pan looks like this

You must be registered for see images attach

that's the 42RLE.

 

[devauxr]

Progress, and possible conclusion. I always hate when someone posts a forum thread like this and doesn't update at the end with what the solution was.

Firstly Leann, Thanks for the pics. I was able to identify the transmission before my last post as I was unfortunately already into removing the valve body when I came to the realization that things didn't quite match up.

Secondly the conclusion to the immediate issue, swapping out the rear speed sensor stopped the transmission from going into limp mode. My thoughts on the code were as follows, the rear sensor was good even though it was the wrong sensor, as the correct sensor has an extension for the magnet that reads the pulses from the rotation of the transmission, so the engine was reading a working sensor but wasn't receiving the pulse data which should match the pulse data from the input sensor which is what triggered the code for the first gear issue. To the computer that data must have looked like a seriously slipping gear box.

As for the original issue, we'll have to see if the speed sensor was the issue. I also changed out some pretty gnarly transmission fluid and filter, so I wouldn't be surprised if the old fluid had viscosity was toast and when it was heated just wasn't doing the job it was supposed to. That would explain why letting the vehicle would remedy the original issue. Either thanks to everyone for their assistance.

P.S.
I still have no idea why that jeep has the 42rle.

P.S.S.
From this debacle I have 3 brand new speed sensors (1 mopar and 2 bwd) that I am unable to return (my fault not the part stores) so if anyone happens to need one, hit me up in the pm's