If my TC is stuck OFF, will my tranny input and output speeds even be valid in a log?

[UrS6]

I am trying to get clear evidence for my warranty co. that my tranny is slipping. I'm going to try to post them here but if my TC isn't locking up will the log even be evidence? Or will the numbers be off because it's not locked?

[UrS6]

I have no idea how to post the logs here. Is there anyone who I can email that could post them?

[905084]

TC stuck off should throw a code. Numbers should still be valid. TC isn't locked all the time. Can't help with the logs.

[UrS6]

TC stuck off should throw a code. Numbers should still be valid. TC isn't locked all the time. Can't help with the logs.

TC code is on. No doubt. But I think it is unlocked all the time because it it fubar'ed. I'm trying to prove that they need to replace the tranny too.

[QuattroRS]

Only way to show the need of a trans replacement is to show that the trans is slipping in any gear or slipping between upshifts.

If it slips and simple test drive is all that is needed. Otherwise replace the TC and call it good.


TC code is on. No doubt. But I think it is unlocked all the time because it it fubar'ed. I'm trying to prove that they need to replace the tranny too.

[ben916]

cruise control test in 5th gear should show all you need.

[905084]

Otherwise replace the TC and call it good.

Why would you EVER just replace the TC? 17153 says the trans A clutch is just a step behind......and you'll be paying for the trans removal.

[UrS6]

cruise control test in 5th gear should show all you need.

How do you do it? 5th gear, cruise control, what should happen?

[ben916]

How do you do it? 5th gear, cruise control, what should happen?

From what others have stated prior in other posts: The trans should be locked @ 50 mph and 5th gear, and you accelerate via cruise button and the rpm's will rise 200-300 without the car accelerating = bad trans/tq

[UrS6]

From what others have stated prior in other posts: The trans should be locked @ 50 mph and 5th gear, and you accelerate via cruise button and the rpm's will rise 200-300 without the car accelerating = bad trans/tq
I can do that with the accelerator pedal. And have done that. I figured it would feel more prominent. In third or forth at 30-50, press the pedal and the rpms go up 300 before the car catches up. Of my 34 cars I've owned this is my first automatic.

and this is an indicator of the tranny? Or it could be tranny or it could be TC? Because I know my TC is bad.

[ben916]

It is more controlled with the cruise control and reproducible with another driver besides yourself.

Also, why isn't your service advisor/tech diagnosing this instead of you?

[TozoM8]

TC slip is the difference between engine speed and trans input speed. Trans slip is when trans input/output speed in not linear. Easiest to see in in 4th (1.000 to 1 ratio). Test it in TIP the TC should be locked.

[UrS6]

TC slip is the difference between engine speed and trans input speed. Trans slip is when trans input/output speed in not linear. Easiest to see in in 4th (1.000 to 1 ratio). Test it in TIP the TC should be locked.

That's what I figured. Probably easiest to see in VAG Scope. My Engine speed vs. input speed looks like:

3744-3104
4096-3424
4192-3744
4416-4000

So I guess the TC is slipping. I'll have to recheck the input vs. output in 4th since I did not log the channel that shows whether the TC is locked or not. The car was fully warmed up and at highway speeds but since the TC is showing the 17125 code up I don't want to assume it was locked.

[UrS6]

TC slip is the difference between engine speed and trans input speed. Trans slip is when trans input/output speed in not linear. Easiest to see in in 4th (1.000 to 1 ratio). Test it in TIP the TC should be locked.

OK. So I just ran a log for the tranny on channels 1, 2 and 7. I got the car as slow as I could in 4th gear (around 1500rpms), tip, and floored it without tripping the downshift. The tach jumps about 400rpms then settles back down. As I get to about 3000rpms i get several "slips" that feel like I hit a tiny patch of ice just for a fraction of a second and then back onto dry pavement. There are about 5 or 6 of these slips over the course of about 5 or 6 seconds. The tach jumps up about 50 rpms each time before it catches and pops back down.

I can repeat this at will and did so 8 or 9 times today on my way to work. The graphic log seems to show the engine and input shaft speeds to follow one another--although the input speed is about 700 rpms less than the engine speed. The output speed follows the other two but, during the 400rpm jump, clearly levels out while the engine and input keep going up.

So it looks like I have irrefutable evidence that both the TC and tranny are bad. Do you all concur?