Fabien92

The pawl park works fine. We hear it when we select P position. In Park we can’t move the car.

FredR

Saddened to note that your splendid efforts to date have not yielded a result but if nothing else take heart from the fact that your efforts have yielded a lot of info as to what is not the problem. I cannot say I am too surprised noting my earlier post but what more else could you have done?

For something to fail in the diff unit one imagines it would have to be something rather violent with lots of bits and pieces in the diff oil. The final element of the PSD unit is a piston plunger system that progressively engages the clutch plates to increase the lock up proportionally from zero to 100% lock so difficult to visualise how that may play a role in your issue. Presumably your mechanic did a simple test to ensure that drive is being passed through the diff input to the output shaft flanges whilst the diff unit was disengaged?

Fabien92

Hi Fred,

We have not try to test that drive is being passed through the differential.
How to perform this test ? Is it possible to remove the differential without to remove transmission ?

We have no bits and pieces in the differential oil.
We removed the rear plate of the differential. All were good inside the differential.

If we disengage the differential unit, in Reverse position we will see the output shaft flanges spin in the opposite direction. Right ?

FredR

Hi Fabien,

If you have looked inside the diff [as I assumed you probably would have] then if there was any serious damage you would have seen it given there is very little in there to see. If the P position locks the pawl then that also indicates hard communication between the transmission and the diff [as I understand] . When one stands back and looks at all you have done logic suggests the only thing that could answer what you see considering all you have eliminated and done would be a complete failure of the torque converter to transmit power into the tranny. How or why this should/could have happened is beyond me as these things are nigh on bullet proof. I am under the impression that you have tested the hydraulic circuits so this leaves me wondering if there is something going on in that system that has been [inadvertently] overlooked. If the torque converter does not work then obviously nothing will happen. The obvious one is the drive shaft turning the torque converter, that question has been asked and as I am aware has been eliminated.

To summarise- no bangs, no funny noises, no metal pick up & no parts grenaded/degraded [to any serious extent]. The only other part you have not checked, changed or pulled apart is the torque converter!!!

gazfish

Does all seem to point to the torque converter, if you had no or very little transmission fluid in it for some reason that might explain why the wheels move when it’s off the ground but you can stop it with your hands. Somebody might chime in on the best way to verify fluid is being pumped into it, only thing I can think of is to run the car turn it off and then emediately open the torque converter drain plug. It shouldn’t have drained back into the transmission and might indicate if its being filled.

Fabien92

Hi Fred,
Hi gazfish,

You're right. The only parts we have not checked is TC.
We will perform gazfish's test.
But as said by Greg, TC never fails ... But don't say never

We can also remove the differtential to check the output shaft.

Any other ideas to test something else ?

I see only three parts : TC, differential, body valve (already checked all ***** and spings / pistons).

GregBBRD

However, he is running out of options, right?
I'm just saying that the most remote possibilities need to be investigated, at this point.

Fabien92

I agree with you Greg.

At this point, we have to check :

- TC following gazfish's instructions,
- Differential and PSD by removing differential to check output transmission shaft when transmisson is working.

By the way, when I shake the TC between my hands (removed from the tranny), I can hear something moving inside.

GregBBRD

Converters all make noise when you shake them.
However, that doesn't mean that something inside didn't break....
Tough to tell, without x-ray vision or without cutting it apart.

Fabien92

Or with an endoscope through the drain plug ?

Schocki

IMHO I would try to get a known good valve body from GB and install it first. This way you don't need to drop the rear axle again and remove the tranny.

AFAIK a failing TC would have given you problems before.

Fabien92

I agree. The problem is my location in South Pacific.

Schocki

Shipping a valve body via DHL-EXPRESS to you is still more durable than a complete transmission via regular snail mail. I don't even know if GB has good valve bodies available on an exchange basis or if you have to mail him yours.

Fabien92

It could be a solution 😉

Schocki

After so many parts have been replaced and checked, it would be a good idea to check the pressures again. If your working/operating pressure is still at only 50 % of the specified value, there is still a problem present.

Checking modulating- and operating pressures is relatively easy and does not requiere a lot of time. I found two videos about the 722.3 valve body, they might be worth watching.