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1996 s420 very bad kickdown

1776 Views 3 Replies 3 Participants Last post by  ac680
I bought a very very clean s420, 80K miles. no warning lights, everything works, seems very well maintained.
This is at an auction, so no driving was allowed.
Bought cheaply for $10K.

Car drives and upshifts very very nicely, like butter, all the gears are there.
In manual mode, no problems, all the gears are there, no delay or slipping on engagement.

However, in D, the normal drive mode, a down shift, from 3 to 2, or 4 to 2 is very very very hard.
from 3 to 2, it seems to engage 1st, and than forcefully execute 2nd gear. From 4 to 2, the same, it engages 3rd first, and 1/4 second later forcefully engages 2nd.
So forcefully that the wheels actually spin a split second, and the traction light comes on for a flash.

I did scan the trans for codes, I have a snap on modus scanner.
It did tell me there was a gear command problem, " desired gear inplausible"
The same for another code, "actuated gear inplausable" or tansmission slipping.

I am going to change the gear shifter in the console tomorrow, with all its switches .

Is this a feasable option?

any feedback?

Thanks, henri.
1 - 4 of 4 Posts
Stop where you are and change the trans fluid, drain the torque converter and change the filter first.. then check for vacum leaks on the actuator lines to the gearbox..dont go messing about inside till you find whats wrong..
There is no logic in the shifter, its in the trans. The shifter only has the interlocks!
there are electronics in the shifter, it indicates to the managment electronics what gear you intend to select.
Replacing this part, indeed cured one error code in the transmission computer, that of inplausible gear selection.
kick down still is horrible, 3 to 2 and 4 to 2 is very very bad.
I did read a service bulletin regarding this, indicating indeed problems with this specific downshift, all indicate front band, B1 has to much play, worn, or broken.
For fluid change, I did this. The 96 trans, has no vacuum lines, nor kickdown cable, unlike the 1995 and previous models.
No external isues apparently, soo electronics, or simply a bad 1st brake band?

any suggestions?

1 - 4 of 4 Posts
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