code po740

[Jlanesey]

All three, I had probed the three wires in the top row, I had read the blue and white is the tcc solenoid. I stabbed te point on my multi meter Into the back of the connectors. Maybe I wasn't getting a good reading, today I will try and send it thru the connector side and see if that makes a change.

I like the idea of a bad ground or wires though. This jeep sat for awhile before I bought it and I have also been getting intermittent (no bus ccd) and no skim popping up.

Any idea where the tcc and the ECM ground to?

 

[Ecomike]

All three, I had probed the three wires in the top row, I had read the blue and white is the tcc solenoid. I stabbed te point on my multi meter Into the back of the connectors. Maybe I wasn't getting a good reading, today I will try and send it thru the connector side and see if that makes a change.

I like the idea of a bad ground or wires though. This jeep sat for awhile before I bought it and I have also been getting intermittent (no bus ccd) and no skim popping up.

Any idea where the tcc and the ECM ground to?

My jeeps are 87-89 Renix, so they may be different, but I recall I think, that the brake switch grounds the power to the TCC solenoid (I could be wrong, it may just open it!!!), but I also recall a bleed resistor not listed in the FSM wiring on that same line hidden in the wiring and a small 2 volt standing voltage on mine when the brake switch was pressed. Never did completely figure out that story, but I did get mine all fixed on all my Renix rigs. If you have cruise control, there are two brake switches !!!!!!

Happy hunting!!!!

 

[Jlanesey]

Also what your satin about converter being partially locked makes sense, when I shift Into gear with my foot on the brake it pulls like it wants to jump (torque converter locked?) this is my first auto. My tj had the ax-15.

 

[Jlanesey]

I'm thinking maybe I should just dc the tcm and see if the noise goes away, if its not getting any power to that solenoid it shouldn't be able to lock?

 

[Ecomike]

I'm thinking maybe I should just dc the tcm and see if the noise goes away, if its not getting any power to that solenoid it shouldn't be able to lock?

That is correct!!!!!

 

[Ecomike]

Also what your satin about converter being partially locked makes sense, when I shift Into gear with my foot on the brake it pulls like it wants to jump (torque converter locked?) this is my first auto. My tj had the ax-15.

What is the engine idle speed in park? It should be 750 rpm.

The TCU-TPS combo should not let the TC lock up till 2nd or 3rd gear at about 35 mph. I say about because it seems to vary with applied throttle, the TPS condition, engine load, and jeep year. It should not lock up at under 20 mph in first gear.

I recently discovered that mine will lock up in 1-2, and 3 positions at lower vehicle speeds (with power to a working TCU...), but in drive it needs to get over 35 mph, in 3rd gear to lock up to the TC.

 

[Jlanesey]

I'd say right at around 750. It does not pull like its gonna stall just feels like it wants to move like if you were to shift a standard and let the clutch out with no gas, just that little bit of pull. Also at a cold start it kind of sounds like a slight squelch is coming from the TC that goes away after about 3 seconds.

 

[Jlanesey]

After talking to the guys at my local tranny shop and explaining the sand like metal deposit I found on my last trip into the pan, they think the clutch inside my TC has failed or is stuck partially locked. Probably from sitting in one place for three years.

 

[Ecomike]

I don't trust transmissions shops. I took a rig in with a clean pan, and they pulled the pan and walked in to show me a bunch of metal crap in the pan, LOL. Oldest trick in the book, they keep junk metal on hand to toss in the pan and show you why it needs replacing/rebuilding!!!

Beware!!!!

 

[Jlanesey]

I don't trust transmissions shops. I took a rig in with a clean pan, and they pulled the pan and walked in to show me a bunch of metal crap in the pan, LOL. Oldest trick in the book, they keep junk metal on hand to toss in the pan and show you why it needs replacing/rebuilding!!!

Beware!!!!

I didn't bring the jeep in yet, only from talking to them did I get the tcc info. These are also the guys who told me about driving it in 3 so the tc won't engage and I can set the monitors to get it through emmissions.

The sand like metal is what I found when I pulled the pan on the magnet the second time i pulled the pan after driving <50 miles. The first time I pulled the pan after I got the jeep <5 miles after sitting for 3 years there was one small piece of debris about a quarter inch long and less than an eighth thick.

From what I have read about the torque converter clutches they are like a paper/carbon material. If that was wearing or stuck partially engaged (low bearing like noise I'm having) it would maybe explain the magnet.

I've been busy with the air conditioning rush at work but when I have some time this weekend I'm going to put fluid in and try to disconnect the tcm and see if that has any effect on the noise.

If there is no change I will pull the transmission and go from there.

Is there any way to test the torque converter or tell tale signs once I pull the tranny?

 

[Ecomike]

These are also the guys who told me about driving it in 3 so the tc won't engage and I can set the monitors to get it through emissions.

Except that the TC will lock up in 3 or 1-2, at least my 87 does.

You need to disconnect the TCU or the power fuse to the TCU to stop the TC from being able to lock up.

Sounds like you have mechanical problems, TC or AW4 or both if you metal in the pan!!!!

 

[Jlanesey]

http://www.youtube.com/watch?v=289IlnbR36o

 

[Jlanesey]

Sucks, probably be cheaper to buy a junkyard tranny then to have it rebuilt, it's really a shame it was rebuilt 10k ago. That's what is making me pray its only the TC.

 

[Ecomike]

http://www.youtube.com/watch?v=289IlnbR36o

It has sound on the video, but all I hear is a quite rig compared to mine, LOL.

 

[Jlanesey]

Replaced the TC problem solved!

 

[QuillsXJ]

Jlanesey, I am literally having this same exact problem! Trying to get through emissions, newly acquired Jeep (98 XJ) been sitting for three years, code P0740, TC noise (especially noticeable when warm), new solenoids, new filter and fluid, etc. etc. So when you replaced the TC it made the code P0740 go away?

 

[Jlanesey]

Jlanesey, I am literally having this same exact problem! Trying to get through emissions, newly acquired Jeep (98 XJ) been sitting for three years, code P0740, TC noise (especially noticeable when warm), new solenoids, new filter and fluid, etc. etc. So when you replaced the TC it made the code P0740 go away?

Yes, exact same issue. I second guessed myself for a month before I but the bullet and did the torque converter. Wasn't that bad of a job and when I put it back together noise is gone, gas mileage is way up, and no more check engine light.

If you drive the jeep in third until the emmissions monitors set you will make it through emmissions, it won't set the code in 3rd and won't damage your trans. I think the problem comes from when the torque converter sits only one half of it remains lubricated and it kills the clutch.

 

[Jlanesey]

This link helped me make up my mind.

http://transmissioncenter.net/Transmission_Noise_Help.htm

 

[QuillsXJ]

Thanks for the info...I just had my trans off like a week ago! See my thread... http://naxja.org/forum/showthread.php?t=1099992 I noticed that the Jeep seems to be going through gas fairly quickly too for an unmodified '98. It's frustrating because literally the Jeep runs and drives perfect! I had some serious metal sand and debris in the pan you can see in my photos. Did yours kind of smell like almost burning trans fluid after driving? Where did you get your replacement TC?

One quick follow-up question also.. how can you legally drive the Jeep enough miles (how many miles about?) to reset the monitors? The DMV in Cali only gave me a one day pass to go straight to the smog station and to go to the DMV and register.

 

[Jlanesey]

Thanks for the info...I just had my trans off like a week ago! See my thread... http://naxja.org/forum/showthread.php?t=1099992 I noticed that the Jeep seems to be going through gas fairly quickly too for an unmodified '98. It's frustrating because literally the Jeep runs and drives perfect! I had some serious metal sand and debris in the pan you can see in my photos. Did yours kind of smell like almost burning trans fluid after driving? Where did you get your replacement TC?

One quick follow-up question also.. how can you legally drive the Jeep enough miles (how many miles about?) to reset the monitors? The DMV in Cali only gave me a one day pass to go straight to the smog station and to go to the DMV and register.

Same smell, same sand on magnets. You will notice your rpm at 60 mph will drop way down once the torque converter locks. I didn't notice any difference at around town speeds only at highway did it really show.

I have an innova canOBD2 scan tool (~$150) that will read all of the emmissions monitors readiness states. It took a few short trips until all my monitors set. I think you could do It in a day. There are some good resources online on how to set the monitors on a Chrysler.

If you just had your trans out I think you should be able to do it pretty quick, it took me like 10 hours by myself, half of that time was struggling with stupid things until I figured them out. I'm confident I could do it in 4-5 hours solo now.

I bought my torque converter from a transmission shop in my town. Paid 220 with a new front seal for trans too. Installing the actual torque converter was easiest part of job I only dropped and slid the tranny back was able to get new one in no problem and had it all bolted back together in about an hour.