There are numerous threads on the OD in the archive. Search & read if you haven't.

Ken C's message covers it well. It's a common problem.

The steps I follow: 1) Is the relay working? if Y, 2) is the OD solenoid clicking? If N, 3) check wiring and 12V to it; once that's OK, 4) pull the solenoid and flush out (12V it open) then flush the ports on the trans. I suck some out w/ a vacuum tester; then start the car and let some fluid blow out. This makes a mess.

There could be a problem in the trans itself but to-date I'm 100% on the above.

Sometimes when I replaced a bad solenoid I've had to take it back off and flush - the ports are clogged from disuse. So now I always flush the ports.

if the solenoid is bad, cut a grove in it and save the money on a bypass plate. Instructions and pics for that in the archives too.

--
240 drivers / parts cars - JH, Ohio

Your OD problem, refusing to go into OD (4th gear), is probably not a transmission problem.

You have to know that the "default" condition of your transmission is to only use the bottom three gears -- i.e., if there's anything wrong with the electrical solenoid controls, the transmission works as a ordinary 3-speed transmission. To go into 4th, the electrical controls have to work perfectly. Unfortunately, on the 240s, there's typically a few potential problems that can interfere.

First and foremost is the control relay (behind the right vents in the center panel, very easily accessible by removing the glove box and just sticking your hand in behind the vents. Do you hear a click when you push the button (next paragraph)? You should if everything is working correctly. Does the light on the dash go on?

Second, the switch (small button) on the shifter -- sometimes its contacts get corroded and the switch won't respond to your button pushes.

Third, a simple wiring failure (failed insulation causing a short or grounding).

Only rarely is the solenoid (for which the IPD plate substitutes) responsible -- and this is the hardest thing to work on or replace, so it should be the last thing you try.
If you hear a click when you push the button, and you see the light go on or off, and yet your transmission doesn't shift down or up according to the light (respectively), only then should you blame the solenoid.

Your OD problem is probably just the relay.

The kickdown cable is, in my experience, rarely the cause of shifting problems. My own method of adjusting that cable is to ensure that kickdown only occurs in the last tiny bit of pedal travel. You can feel the resistance in the throttle pedal when you push past the kickdown detent - you only want that to occur near wide open throttle.

You're doing more good for your transmission by driving it with fresh fluid than anything else short of a rebuild. I also highly endorse Lucas Transfix as a terrific additive for the aw70, and - again, in my experience - dropping the pan to clean and change the filter IS important. The filter screen is incredibly fine and any restriction will cause low pressure and a slow death for the tranny.