My transmission is slipping when shifting from 3rd to 4th gear. I went to the local MBZ transmission Guru and he hooked up his analyzer and said there was a code that says there is no communication from the CAN (car area network) to the Transmission control module. He said the module might be defective, or the problem may be in the transmission. But he suggested replacing the module first.
I really hesitate to spend $950 on a transmission control module only to learn that the transmission is the real problem. Is there any way to test the transmission control module?

PS: Great forum

B52