Kickdown (lack of it) question?

I have a 124 240td 722.3? box with a kickdown problem it does not kickdown to 2nd, kicksdown to 1st or third OK

The car if driven 'normally' drives well, changes up thru gears somoothly using all gears.
When going slowly if you floor the accelerator it kickdowns to first and off it goes thru the gears as you would expect.
At higher speeds when in fouth it changes down to third but that is as far as it goes, it is allmost as if second does not exist in kickdown mode!
select it manually it is there and holds to max revs even if you put the selector back into drive

Fluid is clear and does not smell burnt

I am a tech but auto boxes are an unknown quantity, any that come in are sent to a 'specialist'!

[stevebfl]

Kickdown is severely altered by control pressure/throttle pressure cable adjustments.

[C32AMG]

At what speed, MPH are you going. There is a MPH maximum by design were the transmission will not kick down two gears, it places a tremendous load on the transmission at that speed. You owners manual has the kick down shifts points. if you are within the shifts points then.


Check working, govenor and modulating pressures.

Open the passengers’ side door with the ignition on, floor the gas pedal, you should hear a click at the rear of the transmission if not check the fuse for the kick down solenoid, good fuse, check for 12v at the kick down switch under the gas pedal check for a stuck kick down switch, 12 v; check for 12v at the kick down solenoid, 12v; defective solenoid.

Check and adjust the Bowden cable, check the modulator vacuum lines and connections for leaks check for manifold vacuum at the modulator line.

And the most important vacuum check especially for diesels is a vacuum drop test. With a vacuum gauge connected to the modulator vacuum line, open the throttle, the vacuum gauge should immediately drop to “0” vacuum, if not then you have a bleed off problem which will gave you flared up shifts , slipping and no kick down.

If I am doing 20mph and floor the throttle it kicks down to 1st then changes at 25mph, 2nd changes at 45mph and 3rd at 75mph
which seems to prove the kickdown switch works. It will go on the ramp later to check voltages.

If I am doing between 45 to 75mph it kicks down to 3rd no problem and holds the change to 75 when it changes to 4th again appears to be correct

Its between 25 and 45mph when you feel it should go into 2nd, it changes down to 3rd and that is it! It's certainly within the shift point for 2nd.

The changes up are smooth if driven normally, there is a little flairing if full throttle is used all the way to max rev gear change

I think I am assuming because it works in other gears cable adjustments and vacuum pressure is OK ? I will put a vacuum guage on it later.

(Assumption is a dangerous thing!)

Thanks

Des

[hawkpfc2]

I have this problem on my 300SE 1989 also.

thanks C32AMG

I checked solonoid first, vacuum 2nd, and guess what, after adjusting the bowden cable (shortening the link by about 1/4'' ) I now have kickdown and changedown under load to 2nd.

should have tried that first being the easiest (cheapest?) and quickest check and adjust to do!

This is another reminder not to make assumptions!!!!


Des