Hi All,

Still have the issue with my gearbox thudding into gear usually between 1st and 2nd up and down and locking in 3rd gear with the F on the dashboard which clears with ignition on/off.

I have replaced the fluid and filter and had the gearbox reset however same issues remain.
The usual transmission errors P0781 1-2 shift and sometimes 3-4 show on the Gap Tool.

Car drives fine via manual gear selection which points to the valve body

Final piece of the puzzle is the Valve Body , to remove and replace with a good ZF6 HP26 unit or send mine for repair if possible?

Not sure if the VALVE BODY can be tested fully and confirmed before being put back into the gearbox?

Does anyone know if the valve bodies within all the ZF 6 speed boxes are interchangeable from discovery 3 to L320 sport to L322 ?

And if anyone has actually swapped one out ?

I think a good specialist can test.

Some say the VIN code is stored in the megatonics unit and the result you are always stuck in 3rd. This is bolted to the valve body.

Others plug and play swap.
I would guess it’s important to swap petrol to petrol megatronics units. Or reuse yours.

I Do wonder if you are easing off the throttle when manual shifting? Or a full power shift?

Think the vin is stored in the mechatronic ECU which I plan to swap out, like you say it is sandwiched onto the valve body via a series of bolts.

I could re-program with the Gap IID tool but would rather swap out to replacement valve body if I have too

Be interested to hear if anyone has swapped out their valve body or sent off for testing

New I saw something about this before messing with the gearbox
?feature=shared

I am seeing 13.73v with the engine running

Just went out in the car with the GAP tool plugged in and the voltage showed 13.4v even at 3400rpm

https://www.rangerovers.net/threads/zf-6hp26-solenoid.233225/