5G-auto box oil leak problem

[reiddj1]

Hi,
I am new member looking for some advice.
I have a 55plate SL350 with the gearbox playing up, 93k on the clock and I don't believe the transmission oil has ever been changed. I think I am up for changing the oil but it looks like the oil has leaked at the electrical connector and I believe it is possible for the fluid to go up the wiring to the TCU. Gears sound OK but shift is all over the place so I suspect the TCU is damaged.
Where is the TCU? and how do I get at it?
It looks like you can buy second hand TCU's on e-bay but do you need to change all the wiring as well? can you buy this as a wiring harness?
I am going to take it in to the dealer on Monday for full diagnostics but I can imagine their estimate for the job will be astronomical.
I will change the filter and the Electrical plug housing with the oil change, but is it worth changing the Electrical Conductor plate in the gearbox at the same time.
Appreciate any advice
David

 

[gIzzE]

I would just do an oil change and get a connector and see what happens, you may just be low on transmission fluid. Typical symptoms.

Just draining out the oil from the sump and then refilling will be enough to tell you if you have a bigger problem.

Order a dipstick from Mercedes and see what the levels are at would be even easier.

 

[BlackC55]

What are the issues?

 

[reiddj1]

Oil leak on oil cooler(corrosion) and at electrical connector. Low oil causing gearbox symptoms but it looks like box and TCU are Ok. Still don't know where the TCU is hidden?
Total of 56faults on the diagnostics went on to three pages!!
Electrics on drivers seat now not working and the memory button on the door moves the steering column position if you hold it in -weird! I don't mind oil running up my sleeve but I really hate electrics.

 

[BlackC55]

Fix the leaks first. Don't worry about the TCU just yet. I've seen the work fine when filled with oil.