Gearbox issue

[WillElZiBub]

W203 C220 CDI

5 speed semi auto gearbox

Sometimes, the car refuses to go into 5th gear, and the torque converter seems to slip loads - when accelerating or letting off the throttle, the engine speed varies a lot

When this happens, the C/S switch near the gearstick doesn't change anything on the dash and manually pushing right or left on the gearstick has no affect on the gearbox

Other times, the car drives absolutely fine.

Is there an electrical connector that's known to create this problem?

 

[DSM10000]

When was the transmission fluid last changed? Also, have you checked the fluid level when fully warned up with the fluid at 80 degrees C?

This transmission commonly leaks from the electrical connector on the side of the transmission housing. In severe cases the ATF can track into the Transmission control module and cause problems

It is a fully automatic transmission by the way with a degree of manual override. Not semi automatic.

 

[WillElZiBub]

When was the transmission fluid last changed? Also, have you checked the fluid level when fully warned up with the fluid at 80 degrees C?

This transmission commonly leaks from the electrical connector on the side of the transmission housing. In severe cases the ATF can track into the Transmission control module and cause problems to

It is a fully automatic transmission by the way with a degree of manual override. Not semi automatic.

Where is the electrical connector?

 

[DSM10000]

Where is the electrical connector?

I gave its position in my answer.

It is a large, circular connector, sometimes called a Pilot Bush.

From memory they are under £30 from Mercedes.

 

[DSM10000]

Genuine Mercedes-Benz 722.6 Automatic Gearbox Electrical Multi Plug -

Genuine Mercedes-Benz 722.6 Automatic Gearbox Electrical Multi Plug A2035400253 Part number: A2035400253

mercedesgenuineparts.co.uk

 

[WillElZiBub]

Genuine Mercedes-Benz 722.6 Automatic Gearbox Electrical Multi Plug -

Genuine Mercedes-Benz 722.6 Automatic Gearbox Electrical Multi Plug A2035400253 Part number: A2035400253

mercedesgenuineparts.co.uk

I've bought one of these and the plastic part itself didn't quite fit (even when I took off the seals)

I took the new seals and put them on the original mercedes connector

The car ran beautifully for a couple of hours

But now it is back to running badly again - keeps throwing up gearbox connection issues all the time

Is there something I'm missing?

 

[DSM10000]

Have you checked the fluid level?

 

[WillElZiBub]

Have you checked the fluid level?

Yes. Sat the car till warm on an even surface. Checked the oil level, it's on the high side of the acceptable level (on the aftermarket dipstick).

It's on the top side of the acceptable range.

I've taken the gearbox connector out (but not the inner casing into the gearbox) and sprayed with loads of electrical cleaner a few times to remove any trace of transmission fluid, and will leave to dry for a few hours so the connector should completely dry out - hopefully....

Is there anything else that could be wrong/may need replacing?