Has anyone ever had the cold upshift delay switch going out? It is inside the AT on the passenger side and is vacuum operated. Mine is out, which triggers "check engine" light every couple of days. Any thoughts?

 

I believe that it is actually part of the cable assembly that goes from the throttle to the transmission on the passenger side (the vacuum line plugs into it). Some vendors call this the kick down cable and the price is close to $200.

I believe that replacing it requires removal of the transmission but someone with experience might be able to do it by dropping the back of the transmission but it sure would be tight.

 

You are correct, it's called kickdown cable. One of the local German shops quoted around $200 labor. I will probably do it because even though it doesn't really affect anything, it just annoys me.

 

I believe you can lube it up IIRC although have somebody else confirm this.

 

Code 26 is Upshift Delay Switchover Valve. This is kind of annoying one to fix. The part itself is a solenoid vacuum switch that can be bought on Benzbin for $28.

It is located behind the break booster cylinder in 104 engines.

The odd part, however, is that the switch itself does not go bad very often. Probably the problem is in leaking vacuum tubes either one that come in, or the one that leaves out. They need to be tested first using hand vacuum pump. They should keep pressure of 15 bars for 30 minutes.

If there is a leak, replace tubes first. Only as a last resort, replace the valve itself.

They quoted $250 to fix it all at the dealer.

The function of this valve is to delay upshift of the transmission when the engine is cold. This is done purely for emission control purposes. It cannot hurt engine.

Again, the only annoying thing about it is the "check engine" light.

Speaking of which, do not disconnect battery to reset codes. Here is the procedure to reset them:

Read all codes first.
After the first code is read again during the second go around, wait for 3 seconds and press the button for 10 seconds.
Repeat the last step for each code.
Turn-off and turn-on ignition.

Hope this helps.

 

The switch behind the brake booster is fine. The vacuum tube from the switch down the the transmission is also fine. The upshift delay switch inside the translission does not hold the vacuum. I am 100% sure the diaphragm in it is busted.