P1700 Upshift Delay
 

I have a 95 C280 in the bay that has a CE light on stating that something is wrong with the upshift delay. I have solved a few upshift delay problems but this one I will need more info from anyone who can be of some assistance. This is what I have done so far. I have changed the shift cable of the side of the tranny but even when the car is cold it still does not hold the car in 2nd gear like it suppose to. I connected both of the vac lines to each other located by the overload protection relay and the car takes alot longer to shift but maybe not long enough. I need to know at what temp is the switchover valve energized to let the vacuum flow thru and also what speed will the delay disengage itself so that the car can shift to 3rd. I know speed has alot to do with how soon it shifts so just a ball park will be great. I noticed that the coolant temp sensor was changed so that should be fine.

Thanks in advance

Melvin

You have the wrong impression of how the delay is facilitated. When the car is cold (and I don't know the prarameters) the engine controller switched the switchover valve to place vacuum on the shift cable bacuum element. It continues with vacuum through all chifts under the time interval for delayed shifts is past. It DOES NOT release to cause the shift, it is either on or off. When it is on the vacuum element changes a bellcrank position giving more travel to the control pressure piston thus making the shift later. The amount rpm that the shift takes place is still dependent on throttle position just every shift is later.

The vacuum element is adjustable to make the shifts later or earlier during activation. If the system works but the shifts are still too low the adjustment is probably all that is needed.