I've considered myself pretty familiar with my cars and their AW70 tranny, but I just discovered something today I didn't expect (nor welcome):

Background: First, when I drive around I used the shift a lot -- I use the OD-lockout a lot, and even often switch down in 2nd (in traffic, in slow speed-limit areas to keep the car going slow, etc.). And often, expecting to need some extended vigorous acceleration (e.g., entering a highway's on-ramp), I'll put it in second and also lockout the OD -- thus, I can keep the rpms up as I go through 2nd gear's range, and then manually shift up into 3rd and continue through its range without concern that the tranny will shift up into 4th (OD) before I want it to.

The problem: But I also have a (late VIN) '93 240 that I recently acquired and have been fixing up. So today I took it out for a long ride, and as I was doing my usual "shifting", I discovered that I cannot get it into "OD-lockout" mode -- i.e., the light won't go on with the pushbutton -- when the shift is positioned for 2nd gear! But as soon as I move the shift into "D", it then lets me go in "lockout" as normal. And once in "lockout" in "D", it stays as I put it back into 2nd. Only going into "lockout" is blocked with the shift in 2nd.

I have never seen this behavior in my other cars. And I never expected any "connection" between the shift position and the operation of the relay (if indeed that's the reason). Is there a microswitch that blocks the pushbutton's signal in anything but "D", for instance? I don't see anything in my "green" wiring diagram ('93, late edition) book.

What gives? Is this normal for the late-VIN '93s, is it a defect. I'd like it to go into "lockout" whenever I want it to, as it is in my other cars.

It's a real puzzle to me.

Thanks, in advance, to all.

[P.S. - My reference to "early VIN" and "late VIN" is from my discoveries that there are some changes between '93 cars made early and those made later in that model year's run: e.g., the positive battery cable. So I thought that I should at least note the time frame of it's build time.]