5R55E does not lock up.

[pilotmogge]

Ok, I got my cheap chinese ELM327 Bluetooth reader the other day. I ran it with 4-5 different softwares, freewares or trial, incuding "Torque" in my Android pad.
None of the softwares have reported any errorcodes whatsoever, not a single one!
Not even while O/D lamp is actually blinking.

After driving my 99 ex for a couple of weeks now I Think I can narrow down my tranny problem into just a TC lockup problem. All other functions in the tranny seem very smooth, quite and accurate. No slips or hard shifting as far as I can tell.

I doesnt lock up sometimes, and in some cases it seems do have more difficult to lockup in the slower region, like in 3rd cruising around 30-35 mph than in the faster situation in 5th over 50 mph.

There are Days when it works great without faults, and there are Days when it sometimes fail to lock up, and in some cases the od light doesnt even bother to start flashing...

My hope is that it cant be all dead, since it locks up in more cases than it fails and naturally I wonder where to start looking for the causes.

I've been Reading a lot about this here and on other sites, and found that there are so many other sensor values that are involved in the process that feeds PCM in order to signal the tranny to make the right shifting.
How odd it might look, the problem may theoretically lie outside the transmission, such as Engine/tranny temp, BOO switch, MAF, throttle position or other sensors, or even just a bad/faulty Electric Connection.
Or, is it possible that old oil, or wrong oiltype can cause this isolated symptom?

Where should I start?
How can I assure that necessary sensors give the correct information?
Where do I look for bad Connections?
Can a simple oil flush solve it all?

 

[drdoom]

Go to a shop and get the transmission codes read. Most likely you will need a torque converter at the very least. As you have said though, it is a bit complex, all of the sensors etc.

 

[pilotmogge]

I tried yesterday to retrieve codes with my elm 327 Bluetooth scanner and Torque Pro.

Not a single errorcode whatsoever, not even when O/D light is actually flashing.
Software/scanner seems to work otherwise, a lot of data is presented. I took a 40miles testride and in main part of the cases the TCC locked up as it should do, cruising both around 30-35 and 50-55 mph. But for some reason sometimes lockup doesnt kick in, lets say in 25% of the cases. in those cases often the O/D lamp starts blinking at the Point when TCC lockup shoud be expected, but sometimes it doesnt do even that.

And I almost feel that a more powerful acceleration up to 55-60mph or more followed by a slow throttle release to cruising makes it "easier" for tranny to lockup.

With so many depending parameters, and involved Components Im still hoping for a cheaper solution than a removal and expensive overhaul. I cant get out of my head that its actually working except for in around 25% of the cases.

PCM reset? In order to get the pcm to re-learn drive patterns?

And what about oil-flush? Or electrical bad Connections or faulty sensors?
Its a shame that I cant present any error codes!

 

[2000StreetRod]

closed loop?

The PCM must be in closed loop before commanding the torque converter clutch to lock. You might use your elm 327 Bluetooth scanner and Torque Pro to see if the PCM is in open loop when your symptoms occur.

 

[pilotmogge]

Finally I got a software that read the dreaded p0741 code.

Now it's:
How to proceed from here?