I had this before and exchanged the kick down switch some weeks ago.
I had no trouble so far until yesterday when the same thing happened again without pressing this switch.
Transmission doesn't up shift into 4 and did shift into lower gears with much higher rpm than normal, same as if the switch were pressed.
The condition went back to normal (I was lucky because driving on the highway in 3 doesn't sound great) but then it came again and went away.

So this is clearly not the kick down switch (because I didn't touch it), can it be that the plunger in the kick down solenoid can get stuck causing this condition? Or is something else clogged in the transmission?

Any suggestions?

I suggest you check ATF level and disconnected or leaking vacuum lines.

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X2 on vacuum problem.

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yes, the kickdown switch is known to fail in the stuck on position. you can pull up the accelerator pedal, then unplug it to see if it's the problem.
it could also be the bowden cable, as vacuum is only going to adjust how hard the shifting is, not how long it takes to shift what gear.
if it's not the kick down switch, it would either be the bowden cable, or a bad part internally in the transmission. perhaps a k1spring? not sure.

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It is not the first time I am dealing with this issue.
I don't believe it is the bowden cable nor vacuum or the switch.
As this issue is coming up just once in a while i believe it must be something internal. Therefore I need some advice what this might be and how to solve it.
May be there is a hint: When I accelerate with kick down my rpm are not going up to the 4800 as it should. My shifts are at 4400 max no matter if the
kick down is pressed or not. Martin

That could mean your throttle linkage needs adjustment and possibly your bowden cable is too loose.

Sixto
87 300D

I was dealing with Throttle linkage and some other maintenance this spring.
I was adjusting the throttle linkage as good as I could, also the bowden cable according the book.
I was also changing the vacuum part at the transmission where the vacuum from the transmission comes in.
And I was fiddling with the solenoid because I was questioning that my kick down is functioning at all because the shift points were not going up compared to almost WOT but not pressing the switch. I had the solenoid out and it 'clicks' but still no higher shiftpoints.
Then I was driving and had the same issue: very high shiftpoints and won't shift up to 4 (as if the kick down was pressed, but it wasn't) Then I exchanged the switch and all seemed to be fine until last weekend.
I think it is something internal in the trans causing the scence.
Any comments?

I don't know what it takes to replace the kickdown solenoid but all 722.3s probably share the same part. Try that like you originally suggested.

Sixto
87 300D

Did anyone experience a bad solenoid on this forum? I mean one that does erratic things like mine- do the kick down without actually pressing the switch?

Well replacing the solenoid and plunger is quite expensive (like $200) and I wanted to know if there is more experience out in the world. Martin

I had this situation again today. I don't think I actually touched the kick down switch but the transmission went into the mode of very high shift points like if the kick down circuit were active but it wasn't. This condition bothers me to be honest.
Are there knowledgeable people out there who know about this condition?
Martin

Almost everyone on here and certainly those who responded are knowledgeable. Trouble shooting a complex problem takes effort and step by step isolation of components. I would be surprised if anyone has the magic answer you seek. I would suggest keep listening and trying different things. Maybe even the ones you have already tried. Or take it to the best mechanic you can afford, plop down a PILE of money and let him find it. Good luck. Thanks

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In my mind, I break this down to three scenarios:

1) Rouge kickdown signal to the transmission
a) Sticking bowden cable
b) Faulty kickdown switch

2) Sticking solenoid plunger

3) Sticking component inside the transmission

The causes in scenario 1) are easy to isolate. I'd run a test light from the solenoid to the dash to ensure the solenoid is energized only when you floor the pedal. Scenarios 2) and 3) are more difficult to isolate but maybe we can dig a little deeper. Does it get 'stuck' even if you don't engage kickdown? If you can get it to a condition in which it shifts normally, disconnect the kickdown switch and the bowden cable. Ideally, disconnect the wires at the solenoid itself. Drive around and see if it gets stuck in kickdown mode with both signals out of the loop. If so, I hope your piggy bank is full enough for a likely next step.

Sixto
87 300D

Nice trouble shooting path.

I fully agree.
The last times this happened I didn't touch the KD switch actually....
it just happened. So it was the last time like a week ago. The condition went away for one week and now it is back.
The weird thing is I did a couple of adjustments on the trans this spring:
adjusted linkage, adjusted bowden cable, adjusted VCV, exchanged the modulator, I had the KD solenoid out...put it back..because my shift points didn't go up during KD (should go from 4400 to 4800)...I just wanted to get the transmission up to date and now then this happened..I changed even the KD switch.
I'll go down the list and let you know. Martin

Sixto

It was the bowden cable sticking and slipping back to normal more or less! I cleaned the cable and put some oil on it- works again. The case is closed. Thanks so much.

I need to change this cable as once in a while it started sticking again.
I have bought the cable but there was no o-ring coming with it (don't ask why..) Does anyone know the size of the o-ring needed?