Code 26
 

I just pulled the code from my car and it is 26 - 'Upshift delay switch over valve-open or shorted'. Can someone explain exactly what that means and a typical repair cost? My emmisions inspection is next week and the CE light can't be on.

The normal cause of problems with codes that state open or closed circuit is an improper current flow in the device. To understand when a circuit is closed, whether a device was really there, a dropping resistance in the controller has its volatge measured across. This tells the controller the current flow. A small coil of wire such as the "upshift delay" switchover valve will probably exhibit 250ma to 350ma (I am guessing). The controller probably wouldn't fault 100ma or 700ma if those were the right numbers. I'm not sure why the software guys can't figure out whether it high or low though.

Can I drive around for a week or two with this condition safely and not cause any damage? I can't get the car in the shop right away. The upshift delay refers to the shift points on the transmission correct?

On your 1994 E320, the upshift delay valve delays the 2 to 3 shift when cold.

It keeps the car in 2nd gear longer so that they catalytic converter warms up faster to reduce smog emissions.

There is an electrically actuated switch over valve that is mounted on the firewall behind the brake master cylinder, but I believe that 95% of the time, a code 26 is caused by the upshift delay valve malfunctioning because it no longer holds vacum.

The test is to pull the green vacum tube from the s/o valve, and apply a vacum. If the pressure immediately drops, then the valve itself is bad. It is located on the side of the transmission, and costs about $250.

If it holds vacum, then the problem is the s/o valve and it is a less than $50 part.

Thanks Paul and Steve, That's the info I was looking for!

Here is the procedure to temporaily clear the codes so the CEL is off.

Black 2” box in front of battery
Remove lid
Turn key to run position
Press little button on box
Hold for 2-3 sec.
Code will flash back
Count flashes (26 for upshift delay valve)
Do again to confirm number of flashes
After final count wait 2 sec., and then hold for 8 sec.
Then turn key off and then immediately back to run,
(Do not start the engine)
Wait for 10 sec. for ECU to scan
Start engine after the 10 sec. wait
Keep engine running for at least 50 sec.