V6 Gearbox ECU

Wow Landrover Voodoo!
Will try that as well.

Does it have to be a full moon or is any moon phase ok?

I am trying to get to the bottom of this and it seems Rave says removing power from the TCM (Rave calls this the EAT ECU) performs an adaption reset.


From Rave:
FREELANDER 2001 TO 2004 MY
ONWARDS

WORKSHOP MANUAL - SYSTEM
DESCRIPTION AND OPERATION



Publication Part No. LRL0351 NAS - 5th Edition
Page 44-34

The EAT ECU memorises the signal values of the gearbox sensors and actuators. These stored values ensure
optimum gearbox performance is achieved at all times.

This information is lost if battery voltage is too low, for example if the battery becomes discharged. The EAT ECU
reverts to default readings on first engine start after a battery discharge or disconnection. The EEPROM facility in the
ECU allows the stored values to be re-learnt, ensuring optimum gearbox performance.

If these signals are not within the EAT ECU stored parameters, the ECU will make adjustments to the operation of the
gearbox through the actuators to provide optimum driveability and performance.

Click to expand...

Wow that's very interesting.

Now I'm wondering if that could be the reason why the gearbox gets better if I cycle the ignition (turn it off and on - what can I say? I'm in IT)

I know that isn't the same as removing the battery, but if it's faulty - who knows?

Looking forward to trying this out when the unit arrives.

Thanks for your help - excellent research

Swapped out the ECU today. No difference unfortunately.

Did another fluid change - had just enough left which was darned lucky!
No difference yet but it might take a while so I'll see what happens.

If it turns out to be the speed sensors it's probably beyond my spannering abilities so I might not fix it.

bukko said:

Swapped out the ECU today. No difference unfortunately.

Did another fluid change - had just enough left which was darned lucky!
No difference yet but it might take a while so I'll see what happens.

If it turns out to be the speed sensors it's probably beyond my spannering abilities so I might not fix it.

Click to expand...

So what is wrong with your transmission?

Any error codes? (You need a read better then a simple odb2 to see transmission error codes it seems, this is not confirmed)

What are the exact symptoms?

Ok...

No MIL or error codes via a standard OBDii reader. Don't have access to a Hawkeye or similar.
When I first start the car, the gear changes are fine for roughly 5 minutes.
Then the changes become rough, in every gear except in/out of neutral.
If I stop and switch the ignition off and back on, the changes become smooth again for another 5 minutes or so.
One strange thing I have noticed is that kickdown is always smooth, but changing down due to deceleration is very rough. I avoid this be shifting into neutral before slowing down.

What do I mean by rough changes?
1-2 = thump from gearbox, sometimes takes 1 - 1.5 seconds for the revs to pick up
2-3 = noticeable hickup, i.e. car weight shifts forward then backward, ending in a thump, hard to tell where from
3-4 = thump from rear diff
4-5 = same as 4, not as violent

Before you ask, I haven't tried it with the propshaft off - I ruled this out because of the switch off/on thing.

Any chance of getting a code read to help? We need more to find out what is bad. Did you give any thoughts to measuring the selonoids resistance values with a multimeter ?

Also did you change the center rear diff mount ? That is the thump I got on 3-4 and 4-5 gear changes

All the solenoids measure ok, but I changed the line pressure solenoid anyway.

It isn't the rear diff mount as it doesn't happen after switch off/on - I think (will confirm).

I agree it would be good to get readings, will have to take it to the local dealer and pay £45 for that.
I was resisting but I think it's what I'll have to do!

You should be able to manually inspect the diff mount, it is very apparent. I have not hear about many Freelanders that did not need a center diff mount change after 100 000 km more or less so it might be the same your way. Was it ever changed on your Freelander ? If this was mine I would look at the diff mount first.

I doubt it's been changed - certainly not for the past 90k miles anyway!
Will check it tomorrow.

Checked it today - no apparent wear at all.
No play when I yanked it anyway.

Umm I though for sure the diff mount would have went. I had to remove mine completely to take a look at it to see when the bushing had failed on the two sides.

Let me know if you don't want more theories, I am just trying to give us an idea of what is going on here.

With your odb2 scanner, you should be able to have live data on the temperature of the engine coolant.

Can you co-relate rough gear change with a certain engine temperature? I am wondering if the transmission is changing rough when its fluid is warmer, thus the auto transmission fluid has a lower viscosity. If that is the case, and there are no errors code it could be simple wear.

I am trying to think/find on how to test the speed sensors on the cheap. Nothing is coming to mind thus far. I will keep looking and I look forward to your update on the temperature co-relation.

Absolutely - keep them coming!

I'm out of ideas so anything is good!
Thanks for the help so far.

I look forward to your results. Did you look at the International rescue map to see if anyone with a code reader was near you?

http://www.landyzone.co.uk/lz/f75/lz-international-rescue-map-everything-you-needed-know-191412.html

Based on what you are saying, I am concerned there will not be any error codes to read, thus not too keen on recommending you pay to get them read.

Hmm no specialist diagnostics near me, it seems.

I don't think it's temperature related - if it was, the problem would probably persist if the engine was still hot after switching off/on, but instead it always improves temporarily.

I'll give Taunton Landrover a call tomorrow. They might even give me some free advice - they did once before!
Then again, another time they treated me like scum, so I guess it depends who is there at the time!

One second. I should have asked. Was the reverse piston ever changed on the transmission ? A lot of 1998 to 2003 or so ( no exact dates thus far) jatco 5 speed had issues with that part where the original factory casting was poorly done and developed a crack.

On a Rover 75 this replacement can be done with transmission in car ( I have not looked it up on the freelander )

Nice thread on it : http://www.the75andztclub.co.uk/forum/showthread.php?t=122171

Google
jatco cracked reverse piston
If you want to read more


There is a psi test for it apparently. I am trying to track it down.

Other idea a working (thus returning the correct resistance) but "sticking" solenoid. How is the changing to reverse when cold and after 5 minutes ? I wonder if a sticking solenoid would show up on t4. Hard to tell most folks on Rover just replaced all Solenoids.

Umm something else interesting. A campaign to replace the speed sensor on some of the transmissions. SB125. I got a partial info here. Supposedly you can test for this but the testing part did not make it.

Transmission serial numbers: 0600001 - 1812986

Maybe someone has access to topix that could post this.

http://workshop-manuals.com/landrov...t_harsh_shifts/dtcs_p0715/p0720/p1715/mil_on/


It's on alldatadiy too but I do not have access to that either.
http://www.alldatadiy.com/TSB/68/02682709.html


It would be interesting to perform that test

Ok I think I got it. Test for an open circuit on any of these pins
1 to 2 turbine speed sensor
3 to 4 intermediate speed sensor
5 to 6 output (vehicle) speed sensor

From here. http://workshop-manuals.com/landrov...ifts/dtcs_p0715/p0720/p1715/mil_on/page_3527/

I look forward to your update.