Lets see if i can help. For forward gears the trans needs 2 solenoids powered, and same goes for reverse, so 1 st gear forward, forward clutch "KV"and K1 solenoids are activated 2nd gear would be KV and K2, 3rd KV + K3 reverse is simaliar but instead of forward clutch "KV'' Revere clutch is activated "KR"+ corresponding gear clutch solenoid , the only exmption is 4TH gear forward it uses K3 and K4 to achieve 4th gear forward. So 3rd is not ok but 1st & 2nd are says KV solenoid is ok, 3rd is not ok and 4th is "lacks lock up" now if Y4 was to blame then both forwrd 3rd and reverse 3rd and yes 4th would all have a issue, since you have already check the ohm of the solenoid and it was ok then isssue lys somewhere else. K3 clutch pack? possible but being a higher gear clutch pack i would be leary, how many hours on it? application? and honestly the biggest issue with the zf was cracking of the pick up tubes internaly and eletrical componets,wire,solenoids sensors , so unless you lost a clutch piston seal which would be the 1st i have seen in the 100's of zf i have been into, so what about control valve spool? very possible i have seen the spools stick and cause simialar issues,pulling the valve and cleaning most of the time takes care of this issue. and that leaves the output speed shaft sensor, which is where i would focus 1st, i have seen mutiple problem with these, at the connector the round bullet type pins tend to break off inside the connector itself so you will need to do a continuity check through the connector itself to insure the pins are ok , then theres the sensor itself pull her out check the pick up for debrie and more importantly the depth or clearance to the gear inside. if i remember theres a ohm spec for the speed sensors but cant remeber where i found it perhaps gary has it. hope this helps. also have you tried a clutch calibration? it will throw a fault code if it cant complete which it would detect clutch
pack slippage and throw the corresponding code .
