Ghostty

Out of curiosity a question that have been keeping me thinking for a while:

Has anyone felt something like a "button" at the end when you floor the gas pedal? And if it is a button, what is it for? is it supposed to sort of rev up and downshift? Considering i don't floor it often i ran into that recently when was playing with the pedal.

Das Geld 2

Lol, that’s the kickdown button it shifts to the lowest gear for a proper wot

Ghostty

do they go bad? because nothing happens when i press it

Das Geld 2

it should throw you in your seat and accelerate as hard as possible

bobterry99

The kickdown switch is held in place with snaps and is easily removed/replaced. If it is unavailable as a new part, you can certainly get a working switch out of another pedal.

Rudeney

In the "old days", that button actually caused an extra spray of oil into the engine for help with hard acceleration. Now, it's just a "max throttle" trigger.

Ghostty

Does anyone know what's the correct name? When i drive and depress the pedal literally nothing changes, it keeps accelerate at the same rate, no downshifting either...


Or i should start with a scan of the car?

P.S.

Could the SprintBoost affect the way the delimiter works?

Ghostty

Looked up the accelerator pedal - about $200, not too expensive. Might replace the whole assembly if needed. But will start with scanning for sure.

bobterry99

I presume you would use DAS to see the actual values associated with the transmission controller, and these would include the kickdown switch, I presume. Otherwise, simply remove the switch from the pedal assembly and check its switching acting with a resistance reading across its pair of electrical contacts.

kbob999

Guys - I'm pretty sure the button is not connected to anything...it is just a button with feedback that you are WOT.
I've taken a pedal apart, including the potentiometer for the throttle, and the button had no wiring to it. I wish I could find the pictures to share

Ghostty

Well that would be reaaaaally weird for a button with no connection 😂 but what we, mortals, know about German engineering!

Moto_Guzzi

Does anybody know the design in safety for the throttle, say the potentiometer goes faulty in a way it accellerates max and could catch you off guard-?

Blazeracer

That should be impossible. I don't know about Mercedes, but the GM drive by wire system are triple redundant. You'll maybe get like two 5 volt references that run one high to low and another low to high plus a resistance reference. If all three of their graphs don't match up with the pedal position, the computer goes into limp mode. I did an LS swap in a boat and had to extend the harness out of the pedal to run the drive by wire. It was a lot of wires, I think there were 9 wires total from the pedal to the interface box ,and that was easy way to go.

Bhopkins

I believe this is correct. Last year I replaced my accelerator pedal, and thoroughly tore down the old pedal so I could understand how it functioned. In fact I've got that spring loaded button assembly sitting in front of me as I type. There is noting under that button but a spring.

It seems the only function of that button is to give tactile feedback that you have reached wot.

Rudeney

I have a SprintBooster and the way it remaps the accelerator, I never make it to the kickdown button - I'm already accelerating fast enough before I make it that far. Like I said, the kickdown button is just a leftover "throwback" to the old days. Honestly, I am surprised MBZ still spends the money to install them.

bobterry99

The kickdown button is an electrical switch: K16/6. The Electronic Troubleshooting manual implies it is wired with all M113-powered cars but perhaps not others.

kbob999

Good info! So some pedals have a switch, and some have a button that does nothing!

Ghostty

Ok, so considering you guys own 550 or 55 models and i have a 500 there is still a possibility that mine is connected to something. I will check somehow and post back. Don't know if it will be soon since my next long weekend lands on my trip to Germany...