sirjoseph

So about a month ago I was driving along the highway when out of no where the RPM's skyrocketed and I had to get towed home it was acting as if it was in neutral, I did some diagnosing and I figured it would move when in 4 low. I spent about a week going to salvage yards and I couldn't find any xj's
I finally found one and spent all day today getting the transfer case then installing, it was working and driving better than it did before. I went to the jeep to goto the dollar store and it had trouble starting it would start then die almost immediately I blew off some vacuum hoses but i let it sit for about 5 mins then started it and gave it some gas and held the RPM's up put it in gear and wont move. I got a check engine light P0740 - Torque converter circuit failure, now I had this code before the transfer case went bad but it would never trigger the check engine light it'd be there when you scanned it but no light but it always worked fine. I tried changing the transfer case gears but it still wont move, yes my linkage is fine, no its not the brakes, yes fluids are fine. Is it just a lemon transfer case that worked for a bit? Bad torque converter? Bad Tranny? 250k miles

awg

well you could try disconnect trans computer and see if it works controlled by stick alone....otherwise...this

https://www.transmissionrepaircostguide.com/p0740/

lawsoncl

The P0740 code is for the torque converter lockup solenoid. It's only used once you're at speed to lockup the t/c. It very well could be a torque converter failure, but failure of the solenoid should not cause your non-engagement symptoms. Does the engine load down at all when you put it in gear?

Also, I recommend either adding your Jeep info to your profile, or post it in the thread so we're not guessing.

sirjoseph

Will do! Yes when shifted into gear I can visually and audibly tell the transmission is connecting the drive line somewhere and taking a load, I recently replaced my cracked flex plate around the time the quarantine started, but recently started intermittently tapping, sure enough I checked and its cracked again. One of my initial thoughts were maybe the flex plate cracked in a circle around the plate to motor bolts, since that's what happened last time, but sure enough the flex plate is spinning. I tried unplugging the TCM and shifting manually, no luck, can still feel load on motor. I heard somewhere if you check the trans fluid cold with jeep off it should be to the "MAX" line, once you start the jeep and cycle thru all gears, put it in neutral and the fluid should be somewhere near the "ADD" line, once at operating temps fluid should be at "MAX", I tried and when checking cold with engine running my fluid stays at the max line instead of going down to the add line. What does this mean, is this a sign of a bad transmission oil pump?

awg

you could try a trans pressure test, there is a torx head fastener port on the AW4

lawsoncl

If the flexplate was completely cracked and broken, the engine would not run since the crank sensor reads the outside of the flexplate. The torque converter bolts were intact when you looked? When they back out, they start making lots of noise.

With the trans in D, do you get any noise while shifting the xfer case between hi and low, or any indication that the output of the transmission is spinning? With the trans in Park, does the vehicle roll? If it does, that might point to the xfer case versus the trans.

sirjoseph

I dropped the transmission yesterday, the torque converter rattles when I shake it, I found people online saying that's normal for new/reman converters that don't have any fluid but idk it rattles too much and I couldnt find any info on converters that do have fluid in them. Heres a video of what it looks like and what it sounds like.This has to be shot right? Could this have caused my issue of no movement in gear? https://streamable.com/wxcrje

IJM

How's your fluid level?

sirjoseph

its good

dave1123

Reach inside and see it that inside collar turns in only one direction or both and does it make noise when it does. That's the one way sprag clutch on the stator. Also check the drained fluid for "sparklies", bits of metal. Try a magnet. If there are bits of metal, they could have contaminated the rest of the transmission. It can be saved with a total disassembly and cleaning, including the valve body and solenoid ports. If it was shifting normally before this happened, you can probably get away with using the old clutch packs. Replace any o-rings you find and flush the cooler and lines. If the fluid is clean with no metal, just replace the converter.