http://www.amazon.com/42RLE-Transmission-Solenoid-Block-Chrysler/dp/B00CARVCY4
Does this look like the right one?
Does this look like the right one?
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P0740 ****** code
- Thread starter HoosierJeeper
- Start date
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dude1116
Full Access Member
Sorry. The relearn.
Got the solenoid pack replaced, all was good for a few days. P0700 is back again. It seems like it's on a timer to come on after 2 hours of driving. Shifting fine.
rbtconsultants
Full Access Member
I've been getting that code for a few weeks now, Clear it and it comes back. Mine always comes back when I've been cruising at 70 or 75 on the highway for a bit. Mine is an 02 42rfe. It does not appear the converter is locking. I do the brake tap test and nothing happens. It shifts great into 4th and the rpms drop and it appears to be fine, but brake tap does fail to do anything.
Here's my understanding. The torque converter clutch is triggered by the same solenoid as low/reverse so if you drop into low and reverse fine then the solenoid is fine. There is a valve that switches the fluid flow from the solenoid to the torque converter clutch. The valve is triggered by the jeep's controller when you are cruising at the right speed and throttle position.
It appears there are also codes that should trigger if that valve is stuck open or closed. So, without those codes I assume that valve is working ok also. So my conclusion is that if you get this code your torque converter is on it's way out. I have researched this quite a bit and I haven't found anyone with one of these transmissions that got rid of that code without replacing the torque converter. I've never seen someone replace the solenoid pack or valve body and fix it.
I've read how if the torque converter goes than you might as well have the whole transmission rebuilt because it releases all kinds of dreck when it fails. I'm not buying it. Maybe if you let the converter fail horribly but I have read of folks who's ****** was shifting fine and just replaced the converter and all was good.
I do very little highway driving in the winter so I'm just going to take it easy and wait till spring and replace the converter, assuming it doesn't deteriorate further. I don't expect it to because the big problem, as I understand it, is if you're driving a lot on the highway with the clutch not locking you overheat the transmission and everything starts to go south. I'll basically stay away from trips of more than 15 minutes on the highway and I believe I'll be fine.
Bob
Here's my understanding. The torque converter clutch is triggered by the same solenoid as low/reverse so if you drop into low and reverse fine then the solenoid is fine. There is a valve that switches the fluid flow from the solenoid to the torque converter clutch. The valve is triggered by the jeep's controller when you are cruising at the right speed and throttle position.
It appears there are also codes that should trigger if that valve is stuck open or closed. So, without those codes I assume that valve is working ok also. So my conclusion is that if you get this code your torque converter is on it's way out. I have researched this quite a bit and I haven't found anyone with one of these transmissions that got rid of that code without replacing the torque converter. I've never seen someone replace the solenoid pack or valve body and fix it.
I've read how if the torque converter goes than you might as well have the whole transmission rebuilt because it releases all kinds of dreck when it fails. I'm not buying it. Maybe if you let the converter fail horribly but I have read of folks who's ****** was shifting fine and just replaced the converter and all was good.
I do very little highway driving in the winter so I'm just going to take it easy and wait till spring and replace the converter, assuming it doesn't deteriorate further. I don't expect it to because the big problem, as I understand it, is if you're driving a lot on the highway with the clutch not locking you overheat the transmission and everything starts to go south. I'll basically stay away from trips of more than 15 minutes on the highway and I believe I'll be fine.
Bob
What is the brake tap test? I'm pretty sure my TC is locking...it drives the same as it has for the past 9 years I've had it. Nothing seems out of sorts other than the light coming on. Both times I've had shops do stuff to it (flush one time, solenoid pack the other time) no one has seen anything abnormal in there.
rbtconsultants
Full Access Member
The brake tap test. Cruise in 4th around 50-60 mph on flat highway light throttle steasy for like 10 seconds, this should lock the torque converter. Then tap the brakes lightly, staying stay on the throttle, and your rpms should go up a couple/few hundred. The idea is that tapping the brakes unlocks the torque converter and your rpms go up.
In my case, tapping the brakes does nothing. Seems this means the torque converter never locks so that's why it can't unlock and that's why the rpms don't go up. Hence the p0740.
From what I gather, there is no way you can tell if the torque converter locks just by "feel" if it's otherwise shifting fine. Like I said, I haven't seen anyone solve this without a torque converter If you keep driving it on the highway when you are getting this code you will eventually overheat the transmission, burn the fluid, and ruin everything. *****.
Bob
In my case, tapping the brakes does nothing. Seems this means the torque converter never locks so that's why it can't unlock and that's why the rpms don't go up. Hence the p0740.
From what I gather, there is no way you can tell if the torque converter locks just by "feel" if it's otherwise shifting fine. Like I said, I haven't seen anyone solve this without a torque converter If you keep driving it on the highway when you are getting this code you will eventually overheat the transmission, burn the fluid, and ruin everything. *****.
Bob
I thought going into OD was the same as the TC locking up, which mine goes in and out of OD just fine and when it should.
dude1116
Full Access Member
Mine currently bounces between locked and unlocked up to about 53MPH. After that it locks. Just something you can look out for.
Yours would be due to size of tires and not regeared though I'd say
dude1116
Full Access Member
Believe it or not that's not completely true. My TC is shot for sure. It started before the tires. Get a lot of TC shudder on lockup when accelerating.
You're probably right in most situations though.
Did some research on a Wrangler forum and it seems like the TC locking is not the same as going into overdrive. It should go into OD then a second RPM drop should happen and that's the TC locking. So I guess that's what I need to pay attention to.
I did the brake test and it seems like the TC is locking and unlocking. Held the throttle (going about 55), hit the brake at the same time, RPMs went up by 200-300. Did that a few times. I also noticed the RPMs going up by like 200-300 at the beginning of a slight incline (holding the throttle constant). Is this the way it should behave?
rbtconsultants
Full Access Member
Sounds like you passed the brake tap test, my rpms hold steady when I tap the brake. Interesting though, I would not expect the rpms to go up on an incline unless you speed up since the torque converter locking makes a 1:1 locked connection between engine rpm and vehicle speed. I woiuld expect the rpms to go up on an unlocked torque convertor due to more load, thus more slipping, on the incline. Interesting.
Bob
Bob
I'll have to check the incline thing again. I wasn't intending for it to be a test so I might have subconsciously accelerated a bit or had been going downhill before hitting the incline ever so slightly.Not sure, probably not a fair assessment.
But as far as the brake test, it seemed to pass it. Not really sure what to do next.
But as far as the brake test, it seemed to pass it. Not really sure what to do next.
Did the same brake test today on a 150 mile highway drive at speeds anywhere from 50 to 80mph and every time it passed. My RPMs at 77mph are 2300 (245/70/17 tires same as a 245/75/16). Check engine light is still on.
JeepJeepster
Full Access Member
My torque converter does all sorts of crazy things, and it has since new. Whom ever Jeep had program the 42rle mustve really been an idiot. If will partially start to unlock but get all excited and lock back; then it'll start thinking about unlocking again but NOPE, locks back, then it will actually unlock and the rpms shoot up... then it locks back. All while Ive not moved the throttle what so ever. Its insanity.
Either way, the kj technically doesnt have 'over drive.' Its just a 4 speed transmission with a locking torque converter. Back in the old days (well, not long ago actually) there were 3 speed transmissions with an 'overdrive' unit bolted to the end of the transmission. This is what the 42re, 44re, 46re, etc, had. Then you also had the locking torque converter.
Our 89 grand wagoneer has a chrysler 727 (later to be the 46rh then 46re) without an o/d unit nor a locking torque converter. Its pretty simple, and bullet proof.
That doesnt help you at all....
Either way, the kj technically doesnt have 'over drive.' Its just a 4 speed transmission with a locking torque converter. Back in the old days (well, not long ago actually) there were 3 speed transmissions with an 'overdrive' unit bolted to the end of the transmission. This is what the 42re, 44re, 46re, etc, had. Then you also had the locking torque converter.
Our 89 grand wagoneer has a chrysler 727 (later to be the 46rh then 46re) without an o/d unit nor a locking torque converter. Its pretty simple, and bullet proof.
That doesnt help you at all....
I took my XJ for a ride (96 with the 4.0 and AW4) and for ***** and giggles I did the brake test on it and it behaved the exact same as the KJ did. It doesn't really seem like the KJ is acting up but I don't get why the light is on still.
Update: Replaced the coolant temperature sensor and I've taken 2 highway trips (300-400 miles total) and all seems well for now.
Well it's back. Still no symptoms other than the check engine light. Guess it's dealer time?
Starting to think it's an electronics issue rather than a mechanical one.
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