raggedyedge

Tranny was misbehaving, pulled pan in hopes that replacing electronic components would solve problem but found chunks of what looks like maybe a 2 1/2" plate or bushing. Not sure where it came from. Everything else under pan looks fine.

The 1997 Grand Cherokee Laredo still looks good. Anyone have recommendations on how to proceed? Rebuilt tranny? Junkyard tranny? After market tranny?

Well as I was about to button the whole thing up, I started trying to clean the pieces out of the pan and they were stuck like magnets....huh...they are magnets. All of it. Hey this is the magnet that is supposed to be in the bottom of the pan. Why might it be broken up in pieces.

Well now...do I go back to replacing the electronics that my OBD scan suggested? Or does a busted plan magnet suggest big problems elsewhere? Is there a glimmer of hope for my tranny?

raggedyedge

I replaced the pressure sensor and pressure solenoid in my 42re which cleared the OBD code (45). I left the battery disconnected for 30 minutes to be sure the code was cleared. Tranny seemed good around town and even as I stretched its legs for a quick trip to the dump.

However, when I decided to put it to the test and take a trip out into the badlands on a pretty hot afternoon (over 100) things wen sour. No sooner than I got ten miles from home and turned off onto a gravel road it was like it popped out of gear and made kind of a buzzing noise as I rolled to a stop. Stopped to check things underneath, saw nothing obvious, so I tried putting it in second and it managed to get me back home. Now I'm getting code 45 again. Could I really have gotten a sour pressure sensor that failed so quick? Or is it more likely that something else is at play?

I got the parts at Transmission Parts USA. Very fast service.

raggedyedge

Here is link to audio recording of my tranny. I drove a few miles before it feels like it popped out of gear and generates this sound, stops as soon as I change from Drive to either neutral, reverse, second, first or park.


http://youtu.be/KykNQGUeFo8

raggedyedge

Tonight, I'm going to pump out the tranny fluid and pull the pan again to have a look at the pressure sensor and solenoid since I am getting code 45 again after only driving 15 miles...worked great for those 15 miles. Posted audio of tranny in its "false neutral" state on YouTube.

I have pretty good mechanical aptitude, but this tranny stuff has me mystified and I'm basically just chasing down OBD codes.

Anyone else have a pressure sensor "fail" so quickly? Anything that would cause such a failure? I'm hoping I get in there and find the plug disconnected or something brainlessly simple like that.

5-90

The magnets used in tranny pans are usually ceramic, and therefore fragile. It's quite common for them to break. They may be replaced with any common magnet you like, they're just there to catch any iron/steel filings that may work loose (the first time you clean them, they'll be "furry" from all the filings loosened up as the transmission wears in and the parts lap. It should have little to nothing on it after the first 30Kmiles, unless you've got a problem.)

Just don't use a "shrouded" or "capped" magnet to replace it, or you're defeating the purpose. Just an open small donut, button, or bar magnet will be plenty. You can usually score stuff like that at Radio Shack or your local hardware store for a minimal fee, and you don't need anything special to stick it in the pan - just give it a clean spot and stick it down.

I've often seen these magnets broken, just because they are fragile. I take 'em out, toss 'em, and replace 'em - I usually have plenty of magnets available for any of a number of projects I'm working on anyhow.

raggedyedge

Siphoned out the ATF overnight. Either my siphon tube was a bit small or I lacked enough drop...it came out drip, drip...hence overnight.

Kelley, thanks for the magnet advice. I did put a little bar magnet I got from Transmission Parts in the pan.

Any idea why my pressure sensor/solenoid failed, I.e., code 45 after only 15 miles? Tranny worked great those 15 miles, so i think another one will fix my tranny if I can keep it from failing.

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Bustedknuckle

Could have been defective out of the box. Another new one would rule out that factor. Either way, the TCM isn't seeing the correct voltage back from the sensor.

raggedyedge

Threw some money at it and so far none of it has stuck. Little shy about doubling down.

gmv93

can there be electronical component related problem on transmission controller? may be ,it thinks that sensor was problematic.

raggedyedge

Would that code 45 be related to the overdrive and lockup solenoid?
http://www.transmissionpartsusa.com/...-00053392c.htm

Where do I find this component?

5-90

Hm. How much? I'm paying $16/year for hosting right now, but I should probably kick open an email alias or three sometime in the near future...

5-90

It should be borne in mind that OBD really can only tell you where to start looking. It can't diagnose a sensor mounting fault, ground fault, wiring fault, or anything else.

Most "mechanics" these days are little more than parts monkeys, they let OBD do their thinking for them, and that's what they're trained to do. I consider myself fortunate, I came up on cars in the 50's, 60's, and 70's (GM F-bodies and Y-bodies,) and I'm entirely used to doing my own thinking.

Just because OBD tells you that a sensor or solenoid is bad, doesn't mean it's bad. OBD is simply picking up that there's a signal fault or "signal out of expected range,) and that could be caused by anything (even an unrelated sensor!) Don't get in the habit of automatically replacing parts just because OBD tells you to - it may not be the part that's at fault, and it may not even be that part that's causing the trouble! I can also think of a few cases where OBD was just plain wrong when someone brought a car to me...

gmv93

this is very similar situation to my experience with my Nissan Pathfinder few years ago. Car was up shifting 3rd to 4th with brief vibration at 45 mph.

Trasnmisison rebuilt. i paid lots of money. Performance increased due to new set of bands. But vibraiton returned back after only 500 miles.

Probably problem was only related to a broken selenoid or its controller.
Sometimes it is better to buy a new transmission or a controller than a repair job -especially if no body can properly diagnose problem.

raggedyedge

I got the overdrive and lockup solenoid out, kind of a pain removing the vavle body. I'm wondering how I'll manage getting the manual shifter and throttle arms back on when I button it all back up in a week or so after the parts arrive. Gives me time to think about it. If anyone has suggestions or experience, I'd be glad for some advice. Really challenging to get my hands in there.

I didn't remove the park rod in hopes of avoiding complications with it. So the vavle body is bungied to the tranny housing until I can resume my efforts.

While there I elected to replace the NSS as well. TPS is working fine...at least it tested good.


At this point I'm kind of wishing that I had just had a local shop install a rebuilt tranny. But if I get all back together and it works, I'm sure I'll be happy at that point.

gs69350

Any idea why my pressure sensor/solenoid failed, I.e., code 45 after only 15 miles? Tranny worked great those 15 miles, so i think another one will fix my tranny if I can keep it from failing.

Cascade Transmission parts has an excellent YouTube video on changing the governor and sensor. In the comments, he makes note that several people have been having issues with the governor solenoid not being installed all the way causing problems. I would check that first.