99 S320 will not upshift , w/s switch question

[BamaMB]

My 1999 S320 transmission has started to mis behave. On occasion, it will not upshift from 4th to 5th. The most common is a failure to go into 5th during gradual acceleration. Letting off the gas at 70 to 80 mph or moving the selector from D to 4 and back has no effect. The trans remains in 4th. I found that if I cycle the W/S switch from S to W and back, the upshift will occur the moment I switch to W. The car has 105K and the trans fluid was replaced about 20K ago. What type of switch is the W/S? Is it a normally open or normally closed switch and all you are doing is adding a power signal to the controller to tell it which mode you want. Or is there more involved? Why would that switch cause an upshift to occur? I live in Alabama and I have never taken the W/S switch out of S.

[BamaMB]

I just found this on another site. Please forgive me for leaving MS.com for information.

Gear Selector Switch
The transmission is provided with a selector switch for Standard "S" and Winter/Wet (snow and ice) "W" program modes.

Standard Mode
Press switch on symbol "S". Use this mode for all-regular driving. The vehicle will start out in 1st gear.

Fast On = Depressing the accelerator pedal quickly (not into kickdown position) while driving continuously, rather than depressing the accelerator pedal in the usual manner, will cause the automatic transmission to shift down into a lower gear. This gear shifting process is dependent on the current vehicle speed.

Fast Off = There will be no upshift when releasing the accelerator pedal quickly, e.g. using the engine's braking power during performance driving.

Winter/Wet (snow and ice) Mode
Press switch on symbol "W". The vehicle starts out in 2nd gear, except with selector lever in 1st gear, or with accelerator pedal in kick down position.

The "W" mode helps to improve traction and driving stability of the vehicle. The gear shifting process occurs at lower vehicle and engine speeds than in the "S" program mode.

Caution! Never change the program mode when the selector lever is out of position "P". It could result in a change of driving characteristics for which you may not be prepared.

Important! Always be certain of the program mode selected since the vehicle driving characteristics change with the selection of the program mode. Dependent on the program mode selector switch position "S" or "W" and the gear selector lever in position "R", the ratio of power transmission changes.



Does this sound right? My trans will not upshift problem sounds like the trans thinks I want engine braking and will not upshift. How do I get the trans to stop thinking this and allow the upshift to occur?

[Glide Ride]

I don't know if you ever got this fixed, but maybe this can help someone else.

I have a 95 S320 and it has a switch in the gear shift selector for 4th and 5th gear. That switch broke down, which didn't allow the car to hit 5th gear. 5th gear was restored after I took the wood panel off and reassembled the switch.

Good luck,

Frank