sport/economy mode switch not working

[Gas Guzzler]

Hi everyone,

I have a problem with my '88 560sec. The sport/economy mode switch on the gearbox moves but doesn't change modes. It is stuck in sport mode, which is fine for those quick starts from traffic lights, but doesn't help the smooth starts or fuel consumption

I'm not sure where to start looking.

Any help would be greatly appreciated.

Also, does the sport mode only do the first gear start, or does it also delay changing gear untill you hit higher revs??


Thanks again.

 

[Rog_E]

Cant help you with the switch not working but I can shed some light on what it is supposed to do!

Enables first gear starts (at high throttle openings) delays the up change and improves kick down!

As a first step I would check the integrity of the wiring, after that its time to read and proceed with caution! :?

 

[Malcolm Brown]

Is the switch giving you a positive click when you slide it? If not, the switch top could have become disconnected from the switch mechanism itself - it is only a push fit. This can happen if the gear lever gate assembly gets worn and loose.

If this sounds a likely cause, let me know and I'll take you through sorting it. I've just had a very similar job to do on my W126.

 

[barrie_davis]

Hi Gas
On my 1987 SL (and I think yours will be the same principle) the mode switch electrically operates a small solenoid valve which then connects or vents a vacuum signal to the R/H side of the auto box. Locate the vacuum pipe at the auto box, follow it back to the switch and check for voltage with the engine running: S =0V, E=14V. If OK check the condition of the vacuum pipe it could be disconnected or crushed.
Rgds