kick-down switch sticking?

[Sven]

All,

My 280SL is finally on the road after years of inactivity.  All is good, but yesterday the automatic transmission is behaving like the kick-down switch is engaged (i.e., starting in 1st, wanting to downshift under lighter pressure).  I have tried simply working the switch on/off by hand and aplied some WD-40 in and around the switch to try to loosen it, if in fact it is physically stuck. 1 of out 10 starts is normal, the other 9 are in 1st.

Is it the switch, the solenoid, or other?  Can the kick-down be disengaged (unplugged, unenergized) if need be?

thanks

[jeffc280sl]

From the wiring diagram the kickdown switch is a simple switch and circuit with no relays or solenoids.  One side of the switch is fed from the idle increase solenoid and the other from the venturi unit switch.  I'd clean the switch and terminals on the other units.



Jeff C.
1970 280SL 4-speed

[hands_aus]

I think the kickdown switch actuates the solenoid on the top of the transmission.
That solenoid moves a lever that actuates the modulating pressure diaphragm.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Sven]

Can the kick-down switch simply be disconnected in some manner to prevent 1st gear starts?

[ja17]

Hello Sven,
The plug for the kick down switch is actually inside the engine compartment down near the steering column. Remove the spring clip then simply pull the plug off. The kickdown switch itself can now be unscrewed rand removed for repair.

Joe Alexander
Blacklick, Ohio