Trans Failsafe, any clues.

[Frontman]

Ok folks, bear with me.
I Changed the tranny fluid (ATF 4) and filter after a few Trans failsafe messages and usual limp home mode. ATF was very dark and smelly.
A few months down the line of noticeable better gear changes and the occasional thump on changedown the  failsafe message intermittently returned and has slowly got worse.
It is now at the point where I can predict when it's going to happen. the problem seems to be consistently with heat, as in a 15 min drive in normal temperatures seems to trigger it and its longer in the cold and shorter when warm.
So, I finally got my  1.4.0 scanner running and cleared a few faults including a "thermal oil-level sensor defect" which I changed & cleared all OK.
The " 59 [089] Transmission failsafe program" warning shows up on the scanner in red when its actually in its failsafe and as a Yellow "fault currently not present".
Thanks for reading this if you've got so far. I have spent hours searching for anything that could be the cause, fuses, breathers/air even down to checking (as best as I could with boiling water) the ATF cooler thermostat.
On the 1.4.0. the EGS electronic gearbox control comes up as not found???
Please feel free to comment, it may be something I've missed
Cheers in advance.

[Steamyrotter]

What mileage is on the box??

As I have said before on many a trans failsafe post, you need to measure the gearbox fluid pressure and compare to the drive current

It could be, as mine was, the clearances in the valve body and fluid pump opening up due to expansion when warm causing the pressure to drop off and therefore not feed the box correctly.....

This is a well known and documented issue that you change out a friction material loaded fluid with a nice clean one and you get issues....
The new fluid (and i am not sure what ATF4 is, but you should have Devron3 Equivalent (BMW spec ish) or Dev6 as advised by GM) will be 'thinner' and any excess clearance in the valves and pump will allow pressure to drop.....Also the new fluid will have a cleaning property and will clear out any gunk sealing the valve body up....

This as said can be checked with a pressure gauge on the box.

Unfortunately there is a big chance it will get a lot worse and then affect other things...
The usual suspect is the lack of pressure on the lock up clutch and then wearing the friction material off of that and scrapping the torque converter...  Wish I was making this up, but i have experienced this...

You could be lucky in it being a battery / alternator issue.  How old is the battery and is the charging circuit OK?

Are you actually losing drive yet?  or is it just the fault and lock into gear??

[X5Sport]

ATF 4 is a Chrysler specific gearbox fluid according to web searches, replaces ATF 3.  You may have the wrong spec fluid in there.

As Steamy says, a low battery will also throw up the same error in a random and spurious way and points towards a battery approaching end of life, or being at a low charge state.

[Frontman]

Cheers for the time and effort in your replies;
X5Sport, the tranny fluid is BMW Group Automatik-Getrebeol ATF 4, as advised by Cotswold BMW. It was £25.00 per litre and I took it that not skimping on a recommended fluid was the way to go!!! if all this could be caused by the wrong fluid I'll be sick!!
Battery's new and charge is good.
Thanks again for your input.
Steamyrotter; "measure the gearbox fluid pressure and compare to the drive current" I'll have to come back to you on that one. Battery and alternator ok.
The X5 drives great before the failsafe kicks in, changes up and down are smooth and the acceleration is unbelievable.
Cheers again for your time.
Col (I'll be back).

[Steamyrotter]

You will need to get a gauge fitted to the pressure tapping on the box ala page 16 of the manual from

http://xdrivers.co.uk/forum/index.php/t ... l#msg22270

then using a scanner or some other similar tool you need to see hte drive current to the pressure regulator solenoid and compare the readings with the table therein....

Its easy to do (the tapping point is an M10 Fine thread btw.) as long as you have the tools..

I added a pressure transmitter on mine and wired it to a pic driven LCD display to get continuous pressure reading as i am so paranoid about it.....

That is covered :-
http://xdrivers.co.uk/forum/index.php/t ... #msg102513

regards