Actually I think he is referring to the decel switch and I'm not sure what it does overall. I suppose its intended purpose is to signal closed throttle fuel fuel cut-off under deceleration.
It also plays a part in closed throttle recognition for idle control. I've never been exactly sure why they needed a second idle recognition switch when they also had the throttle switch doing the same thing.
I'm guessing this is what is being talked about as the throttle switch is not visable until disassembly.
Bosch Master, ASE Master, L1
33 years MB technician