Dear all,

If this tread is in the wrong forum section, please move it. Also, if this issue has been discussed before, please notify me. Thx.

My Daimler D6 drives absolutely fine when the engine is cold but after about 15 minutes, the 4L80E transmission changes gear at about 3000 ~ 3500 RPM. Could this be a ATF problem (level is OK) or should I look into another solution?

Thanks for your advise.

I've moved your post to the x305 section Graham pointed you at in your intro.
Hope you get some useful help.

Ideally you could find a transmission specialist with the right diagnostic tools who could check for trouble codes and monitor the electronics of the transmission: shift solenoid operation, speed sensors, etc.

I don't have a solid answer but will throw out some thoughts.....

Check the harness at the rear of the transmission. The trans mount often wears and allows excessive transmission movement causing the harness to stretch. This can damage the wiring connector. Fairly common on the X300s with the 4L80E.

A faulty throttle position sensor can cause shifting problems.

The 4L80E has two shift solenoids ("A" and "B") and two speed sensors (input and output). All are known to give trouble. If it comes down to experimenting replacing all four wouldn't be an unreasonable guess. In the 'States the parts would be about $100. Labor would probably be 2-3 hours. The speed sensors are external. The solenoids are internal...the pan has to be dropped to replace them.

You can Google "4L80E Late shift" and see tons of info. Virtually all will be in reference to various GM trucks, as that's the most common application of the 4L80E, but you'll likely pick up some good info.

Sorry I can't give you any concrete information

Cheers
DD