Check Engine Light returns?

[dwight hinton]

My 92 500E continues to trigger the check engine light.

As best I can remember the diagnostic codes are
-crankshaft position sensor open or short circuit
and
-right upshift delay switchover valve open or short circuit

The car still runs perfect. Each time we clear the fault codes, the problem returns. Sometimes it takes weeks, Sometimes it takes only 2 days.

The car is box stock except for K&N's, slotted rotors, and a modification to the tranny, the valve body was modified to improve first gear starts. It was done by a local tranny shop who does a lot of MB tranny work but I am not certain exactly what was done. It does kick down a little sooner but the change is not radical as the car often does not start in first gear. As the tranny was out of the car for other reasons, the modification was not very expensive.

Any suggestions.

[mbdoc]

Up-shift delay means the trans didn't hold in gear long enough durning the warm-up period. This is a common failure. Controlled by a vacuum element in the control pressure cable.

[dwight hinton]

Thanks for the prompt response. How difficult is this to replace?


Also what is causing the crankshaft position sensor code??
Is it possible that the vacuum element is causing both?

Thanks

Dwight