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I have owned this car for three years now and asked my mechanic about this but he hasn't been able to answer.
The S/E switch on the console doesn't do anything. Gearbox response is leisurely, except when the car is cold, and changes are early so I think it's permanently in Economy mode. Also, it often doesn't kick down when needed.
I have to take it to have some work done next week, is there anything I can do to have this fixed?
Last edited by deeuutee; 10-22-2022 at 04:44 AM.
Reason: added pictures
I thought the switch might work like the cold start function to help the catalytic converter reach operating temperature. That starts the car in first and delays upshifts to higher engine speeds. That makes the car really lively to drive - until it gets up to temp. That's what I want.
Found something relevant:…the mechanically controlled automatic transmissions used before 1996. Those transmissions used a throttle pressure cable (control pressure) for determining shift points under various loading. In order to heat the CAT and reduce the cold running time, Mercedes used an electrically controlled, vacuum-operated bellcrank-type lever action to change the capabilities of the control pressure cable. In other words, when cold, vacuum at the switchover valve is switched to a vacuum chamber at the transmission end of the shift cable. There, the actuator movement changes the effective length of the cable. The common problem here is the diaphragm in the actuator element, but testing is simple.
The first test is to see that vacuum is at the switchover valve when running. Next take the line to the transmission from the switchover valve and apply vacuum. In the common failure, the element won't hold vacuum, and you're done with diagnostics.
If the vacuum element holds vacuum, then you must tee into the line at the element and evaluate the vacuum when cold. If there is vacuum at cold running, and a code is present, then evaluate the shift against the criteria. The element is adjustable on the replacements and the cable is always adjustable. A poorly adjusted shift cable adjustment could make the added shift delay not large enough to satisfy the controller.
So I took the car to be serviced and have the front brakes done. One side squealed after this so took I it back. Squealed again, took it back again. Squealed again, took it back again.
And yes, it was squealing again, so once again I took it back. I mentioned the gearbox problem, and he said that's how they are supposed to work, they will only kickdown if the floor switch is triggered.
Anyway, this time he had the car for five days. When I picked it up, he said the gearbox is much better now. And it is, I think he also did some engine work, but anyway the performance is way better, than it was. Much quicker off the mark, and gear changes happen much quicker when I put my foot down.
No charge for any of this btw, or for the four extra rotor and pad changes.
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Pad had started squealing again tho...
If you remove pads and put some new copper paste on the back plates they might get quiet?
Have you checked if your pads are worn?
How are the rotors?
Are they worn or warped?
Make some test braking on a straight road where there is no traffic.
Speed up to 50 or 60 and make some pump braking but not to a complete stop.
See if yo can shave off the glaze?
Repeat a few times and see what happens if it helps or not?
Some pads do squeal and they can be very annoying.
Every one will turn their heads when you hit the brake which doesn't look good for a Mercedes.
I think if your pads are glazed this happened from heavy braking under a period of time and they cooked?
Friction material got hard from heat.
Just a guess.
10-22-2022, 01:47 AM
