A4LD problems

[Henri56]

here the summary table in english

 

[transman304]

I really don’t know how to explain it to you the TCC operation will not cause you to loose a forward gear. With the TCC unplugged you would still have 1-2-3-4 gears. Sorry that’s the best I can explain.

 

[Henri56]

ok I want to believe you and thank you again for trying to help me but if it is not the tcc , I do not see what the problem is

 

[CDW6212R]

Third gear has the high/rev drum active that is not applied in first or second. Converter clutch will have zero effect on gears 1-4.
Brad

Brad posted what drives 3rd gear, I didn't know which clutch drum that would be in the A4LD. So there's something wrong with the high/reverse clutch drum, or the circuit that engages it. That's what all of the other work was for, to be sure the VB and accumulators/springs were in good shape and working. It might be he clutch drum itself, the piston inside with a bad seal or the check ball that holds pressure in etc. These are details of the internal building of an automatic. I think you have done all that can be, without taking it out and opening it up fully.

 

[Henri56]

Would it be possible for the hight/rev clutch to run in the rear and not in the third?

 

[Henri56]

No one knows how to answer ?

 

[CDW6212R]

Each gear is created with a combination of subset assemblies, so 3rd gear is different than reverse in some way. The chart you found above isn't the typical chart I've seen to display how each gear is obtained. So that one doesn't clearly show how the 3rd gear and 4th gear differ.

The VB is part of every gear selection, so that is possibly the one thing left which could be causing the 3rd gear to not engage.

I don't know what the pressures that should be in each gear, that would be part of an advanced trans shop diagnosis, the trouble shooting that might point to the problem before taking the trans out. I'm limited greatly by not knowing the deep details of what trans techs learn about how various transmissions work. So I'm sorry that I can't help you more.

 

[Henri56]

yes I understand , the gear could turn in one direction and not in the other for example

 

[CDW6212R]

It's usually a combination of one or more clutch drum sets, and a band etc. The reverse obviously uses the reverse band, so that band shouldn't be the problem for example.

 

[Henri56]

I don’t know if I can solve my problem but I thank all those who try to help me for their patience in trying to help the people who need it

 

[Henri56]

Aiiie , the it’s dead , starting the engine , the accelerator petal was set and the engine mounted 1 second at 7000 rpm , too late now I no longer have any speed either front or rear , believe that it’s screwed for good

 

[CDW6212R]

Do you mean the throttle stuck open? That would be super rare, the cable or throttle blade sticking should not happen. Take a break and don't think about it for a while. Sometimes they need to set a while and we need it too.

 

[Henri56]

I wanted to check the throttle valve and I put it back wrong , the accelerator was fully open , when I started it went up to 7000 rpm direct , it only lasted a second but I think it was enough to break something in the box

 

[Henri56]

small test today , the level drops with the engine running so the pump always goes , when I put in reverse or before , the engine speed changes but no thrust , and we hear a slight friction , an idea?

 

[Henri56]

7000 rpm could cause overpressure and tear the seal of the vb?

 

[CDW6212R]

When it's in park the VB isn't much a part of what's going on in the trans. Then it's more about the pump.

I wanted to check the throttle valve and I put it back wrong , the accelerator was fully open , when I started it went up to 7000 rpm direct , it only lasted a second but I think it was enough to break something in the box

Did you possibly have the manual valve in the trans connected wrong? That could be what's up with it now not going into any gear, the manual valve has one slot where it engages the throttle lever to work, anywhere else would not do anything.

 

[Henri56]

I think it’s misunderstood, the valve I cleaned is the one in the red circle

 

[CDW6212R]

Ah, that's the TPS sensor, it just tells the computer where the throttle is. It doesn't need to be cleaned, but with some engine running issues, it might be tested to verify the proper voltage curve.

 

[Henri56]

good , pressure test gives 0 , pull the chiller line no oil circulation so the pump is the problem , you have to pull the box completely to replace it or is it possible under the vehicle?

 

[CDW6212R]

Yeah, sorry to hear that. Yes the trans or engine has to come out to R&R the torque converter, and the pump.