I picked up a 99 E300 a couple of months ago that was in limp mode. I figured it should be an easy conductor plate swap. While replacing the conductor plate I also test the shift solenoids and all seemed to test OK. Put it back together, cleared the codes and reset the adaptations and took it out. It seems to me like the trans is starting in 1st, shifts fine, but when it tries to shift to 5th it does upshift. I can feel it reducing power slightly in preparation for the shift, but never shifts. From then on it seems like it is starting in 2nd. When checking codes, I get codes 055 gear comparison negative, target gear not achieved, and code 151 sporadically gear comparison negative, target gear not achieved. In doing a little research I came across the ETC manual for the 722.6 which seems to point to it possibly being the shift pressure regulating solenoid being stuck or defective. I guess I am going to pull it back apart and check it out but I am doubtful as it seemed to test good when I had it apart the first time. Maybe there is some contamination causing it to stick. Anybody BTDT? If it comes down to it I may have to head out to the PNP and harvest a valve body. Will one out of a E320 or similar work? I was thinking the shift points and such would be controlled by the computer and not the valve body itself.

Watch the scan tool and move the shifter. This era had problems when liquids were dumped in the console.

If you put the shifter in 4 th and drive, does it operate normally?

Did you pull the trans computer and look for oil in the connector / board?

Scan tool shows gear selected with the shifter and I am not getting any shift module codes.

Car does the same thing regardless of if shifter is in 4th or drive.

I did have some oil in the trans computer which I cleaned out of the computer and the harness connectors

You might have a rear end ratio problem. From others posts, the trans goes in to limp after the 4th gear shift if it sees a overall ratio problem. ( 4 th is direct drive )

Try to drive the car in 3rd

Have a look at the trans controller and ABS part numbers / version coding, I'm wondering of someone mix matched parts.

There might be a grounding issue, others have had odd electrical faults.

I have a 97 E320 parts car that goes into limp. When that occurs, the high beam indicator lights up , left fog light turns and some sort of warning pops up on the dash. Haven't tracked it down since it is a parts car.

I will check that out