W202 c180 Autobox change-up problem

[ydidibuyit]

My 1998 C180 Estate drives good for 155,000 mls but has recently developed a gearbox problem. The box appears perfect but on a couple of occasions and after using reverse gear, I select drive and the car pulls away fine but remains in first gear. When I stop and run the selector up and down the problem disappears. I took it to a garage and they checked the ATF and said that it was as clean as a whistle and at the correct level but they could not explain the problem. I must point out that there are also times when I use reverse and the problem doesn't occur so it is quite puzzling. Any advice appreciated, thank you.

 

[NW_Merc]

Have you had the fault codes read?

 

[mauno]

speed sensor

 

[ydidibuyit]

Hi, thanks for your reply.
I haven't had any fault codes read but can do if you think it might help. I have nothing showing on dash (No warnings)

 

[ydidibuyit]

Hi, thanks for your reply. I don't know anything about speed sensors. Could you give me a brief idea why that would cause my problem, how are they related? If I tell the garage will they know? Given that they seem to be head scratchers... lol

 

[mauno]

speed sensor tells the gearbox that the car is fast enough to switch up.also stepper motor/hydroelectric plate causes same problem.car goes forward,reverse but no change up.if other problem like a solenoid would be faulty it would not start to drive

 

[ydidibuyit]

Mauno, thank you so much for your prompt and very concise answer. Now I can set about having it looked at. It helps if you know what you're talking about (or sound as though you do) when speaking with my garage. They work on a two tier pricing system... one price if you know a little and a much higher price if you know nothing... lol.
Thanks again.

 

[BlackC55]

The speed sensor codes are flagged up as a comparison issue between the two sensors.

There are no stepper motors in this gearbox too by the way.

Just get the gearbox codes read.

The sensor plate is about £200plus vat and fitting. Budget for fluid and a sump gasket too.

 

[mauno]

as black says too code read first with sds ( I can help with that if you close to essex). then see how much it will hurts