Since TexasHonda had mentioned possibly changing tire sizes to "fool" the PCM by equalizing the speed sensor readings, whereby the PCM wouldn't throw the P0740 code, that got me to thinking.

I noticed the other day that my GPS was reading a different vehicle speed than what showed on my speedometer, speedometer was reading 4-6 mph higher than GPS reading. Now, while its quite possible that my GPS isn't calibrated correctly, I highly doubt that, since it takes its readings from multiple satellites at once, an accuracy I would compare to an atomic clock. And so, if my VSS was reading vehicle speed inaccurately, wouldn't that result in an improper comparative analysis in relation to the main shaft rpm's, which would cause an invalid P0740 code to be thrown?

I'm beginning to doubt whether I can accurately determine the physical operation of the lock-up clutch while driving. If it is operating normally and I'm just not sensing it, and my PCM is throwing an invalid TCC fault code, could that mean that there isn't actually anything wrong with my transmission after all? It is shifting perfectly.

I know I'm thinking about this way to much (at least that's what my wife is telling me), but is this even possible?

Thank you!

 

There are different speed sensors than VSS; the mainshaft and countershaft which are used to detect P0740. Both displayed car speed and countershaft speed would be affected by tire change. You would need to reduce countershaft speed by increasing tire size to attempt to "fool" the ECU on code P0740. Not sure how much difference would be required to fool under most driving conditions, probably 5-10%.

good luck

 

Thank you, TexasHonda. I'm just trying to diagnose everything possible before taking car back to transmission shop. I'll probably end up doing just that, because as was mentioned, I shouldn't be satisfied with a permanent P0740 code right after a rebuild.

 

So I decided to drain my rebuilder's "Honda fluid" for actual DW-1, and when drained and measured, what came out after about 15 min. was 4.5 qts. I was performing the 3x drain/fill procedure, and I thought that was strange because the specs, and previous experience with similar engine sizes, says you will only get @ 2.6 qt. from a drain procedure. It seems that there may be a "leak" from an internal seal that is allowing fluid to continue to drain from the torque convertor, which I didn't think was supposed to be possible. As I replaced the drain plug for a few more minutes after draining reduces to dripping, then remove plug once again, I get a fairly strong fluid drain once again, as if fluid has built up to drain out, from where I can only imagine.

The good thing, is that in my drain/fill procedure, I only had to do it 2x instead of 3x. The BAD thing, is that if the torque convertor is "leaking" in any kind of way, then that may explain why I'm getting a P0740 TCC code.....because while it is failing when it attempts to apply distinct fluid pressure with the torque convertor, but this pressure is leaking out into the outer transmission housing, thereby reducing the pressure required to sufficiently apply the lock-up clutch.

If that code represents an internal fluid problem, then maybe some kind of bypass or leakage from the torque convertor during normal operation could be causing a problem with the lock-up torque convertor, housed inside that unit. I'm just thinking that if its possible for me to drain my entire transmission with enough patience, then something must be wrong.

Can I get some opinions about this please? What is the specific seal that should be preventing the fluid from moving from the torque convertor housing into the main gear housing. Thank you much.

 

The transmission is probably the most complicated part of your car. The specific seals are beyond me. I really think you should let the shop that worked on it try to fix this.

 

Most definitely, PAhonda.....its SO going back. I'm just trying to get all my ducks-in-a-row before I go in, to be in the best shape possible so that I can explain, defend, and expect a mostly pleasant re-rebuild when all is said and done. I'm not going thru this a 3rd time. It was easier having my first child. I know that may not be saying much about my first child, but I...do...not...trust...auto...mechanics...TY!

 

I didn't take it back, for fear that he would say the P0740 code was a sensor problem and so not covered under his rebuild warranty. Alas, it got towed back anyway, after a main seal burst on the highway, leaking out most fluid as I got off the highway and positioned it for a proper tow hookup. Thank God it began leaking out on the exhaust manifold, so I was immediately able to see smoke in my rear view mirror, put into neutral, and get off highway before it wouldn't move.

So not to give him a "way out", I cleared the P0740 code while waiting for the tow. No problem. They ended up replacing the pump, the stator, and the main seal, "just to be sure" was the only explanation. That, and a poor seal must have busted when a pressure line got clogged or something.....I figured they messed up the rebuild job in some way that allowed the pump to create excessive fluid pressure in there which finally caused the seal to burst. During the 2nd fix, they must have seen what they did, or didn't do and fixed it, but didn't want to admit that they did it wrong the 1st time.

Either way, it runs and shifts very smooth now, no codes, and noticeably better mileage (24mpg city as opposed to 20mpg before final fix), and I definitely notice the lock-up clutch engaging now (which explains the better mileage).

Problem solved. Thanks for everyone's input.