I have a copy of the Jatco JF506E parts diagram from Automatic Choice and this:
Autobox( diesel ) solenoid Replacement
First job is to make sure you do really need to do this job. So get hold of a multimeter with resistance facilities and twist open the large cylindrical connector on the passenger side of your engine bay. There are two there , its only the large one that concerns you. Test resistances accros the male pins side of the connector. They should match FIGURE 6 in this document http://www.muddyoval.com/1articles/f...20Part%201.pdf
So you should have found one or more of your solenoids faulty,,, its time to go in !
On hand you need At least 1litre of the correct ATF 5 litres if you plan to drop the oil at the same time, the solenoid/s you beleive are faulty and ideally some gasket goo. A 10mm ratchet setup for cover bolts and ideally a 10mm ring spanner 8mm socket to move coolant header tank. Flat head screwdriver for air pipes,cableties to tie them back temporarily.I found a butter knife and hammer usefull for breaking the cover seal.
Ok so to start make a bit of room for yourself above the black solenoid cover . I undid the jubilee that joins the intercooler pipe to the EGR (Exhaust Gas Recirculation Valve)
/the jubilee that joins the large silicone intercooler pipe to a metal pipe just above the casing and moved the coolant header tank off to the left, dont worry about keeping it level. Cable tie anything else back there are some plastic sheathed wire looms down there and some coolant pipes.
Now you can start undoing the 20 10mm bolts surrounding the cover. You will have to access some from underneath .When all thats done you will most likely need to drive a butterknife or similar impliment behind the cover at various points just to loosen the seal and enable you to remove the cover. Be carefull at this point as oil will come out from the solenoid chamber even if you have dropped it from the drain.
Ok cover off you refer to this document and locate your faulty solenoids whereabouts http://www.automaticchoice.com/Catalogue/jf506e.pdf
Exploded component diagram on page 448 shows solenoid locations list on 450 shows which solenoid it is in relation to diagram i.e 708 is 2/4 duty solenoid. You can now unbolt solenoid and replace carefully, make sure not to introduce any Foreign object debris into the gearbox.
Now clean the face of the cover and wipe the oil from the box flange . Bead of liquid gasket around the cover and bolt it back on . Top up your oil if needed and away you go .Replace all your air hoses etc and your done.