Das Geld 2

Hi Guys,

I won't have access to my SDS until next week and recently have been experiencing an issue with my car. I could be driving and randomly the car will stick in a gear 4 or 1st and the only fix is a restart and it goes away.

This has been getting progressively worse. Yesterday was the breaking point the check engine light came on and any shift into R or D is hard and the tiptronic doesn't work and is stuck in 1st..no restart fixes it.

At first I thought it was due possibly to maybe a bad connection to the shifter electronic connector -couple months ago when I had the stuck in park issue I removed the plastic piece and that is when this started happening. I rechecked those and they are all fine, I pulled them and reseated them to no avail.

I searched the forums but have not found a same exact issue, but similar stories of a gear being stuck with a check engine. Perhaps someone can shed some light on this before SDS comes into play.

Thanks!

Jack_88

You don't have oil that's wicked it's way up to your transmission control computer in the engine bay, do you?

Das Geld 2

Hi Jack,

Did extensive research and found out what it is most likely.

A leaking O ring which probably got to the electronic conductor plate!! The oil or small shavings are probably screwing it up and thus the car reacts this way.
I'm looking for DIYS as I type this. I wonder if it was preventable..?!?

Thanks!

tusabes

this is my guess

if fluid has damaged your conductor plate or tcu yes it was preventable by changing the electrical connector see the first video here

https://mbworld.org/forums/s-class-w220/608957-w220-how-repair-videos.html

Das Geld 2

Thank you all for the advice

I ordered an electronic connecter (pilot bushing)

This is the code I got on star..upon clearing the fault the car shifts normal...


I will install and see if this will make the issue go away

Jack_88

Changing the bushing will not alone solve the issue, if that is the problem, you will need to clean up the TCU as well. Oil wicks it's way up the wires, through the connector, and straight into the TCU. Mine had a tablespoon or two in the TCU when that part failed, and I wasn't yet having symptoms.

Das Geld 2

All the way in the engine bay? What is the best way to clean?
I know my electronic conductor plate might be an issue as well.
Won't know until I take it apart.

Jack_88

Yes, all the way in the engine bay. I wouldn't believe it if I hadn't seen it myself. Electrical contact cleaner is your safest bet to clean it with. If you have oil in it, it will be obvious from the connector.

Das Geld 2

I just came from the shop.

we checked the wiring harness and it had a bit of oil but according to them no leak! They cleaned the harness with carb cleaner and put it back in place.

get this I couldn't put on the new pilot bushing because the thread was seized on the inside of the electrical plate..so that bolt kept spinning through.

i guess if a code or limo mode comes back it's plate time.

Jack_88

If the wiring harness in the engine bay had oil in it, it's leaking. No ifs, ands, or buts about it. It's not just the wiring harness that will have oil in it, it will have gotten into the TCU, and that needs to be cleaned as well. I can't help you with the stripped thread, though. I'm not sure if you were saying the old bushing wouldn't come out or the new bushing wouldn't go in. The bolt on the inside doesn't thread very far, and if you don't grease up the new bushing it won't go in far enough for the threads on the new one to catch. I tried putting in my new one without greasing it and even though I though it was all the way in, it wasn't until I greased the O-rings with dielectric that it slid that last tiny bit in so the threads would catch.

Das Geld 2

thanks jack, will check and report back 100%

When they took of the oil pan it was all dry up to wire and that's why they determined no leak. I made them look at the harness contact anyway(the part that goes into the bushing ring) that part had a oil resiude.

Yea i I was referring to the old bushing they couldn't get it out because the bolt kept spinning through..I never got the new one on. They just sprayed carb cleaner on the contact and connected the wire back on.

they actually had an old electronic plate there and showed me exactly what the issue was with the bolt.
Ill take their word for it as they said they've done this hundreds of times. So pretty much nothing got done.

later in the day - shifting error came back..

just ordered the plate :/

Jack_88

Fair enough. It's the connectors to the TCU in the engine bay that needs to be checked. You can do that yourself, just disconnect the battery first. The TCU is the small black module in next to the fuses, it's very easy to access. It has two identical connectors with a bunch of wires coming out of them. Simply flip the gray lever and the connector comes right off. The TCU isn't held in by anything, so you can pull it straight out and look at it. Disconnecting the battery is the hardest part, if that gives you any idea as to how easy it is to check. If they are replacing the conductor plate, make sure they put in the new pilot bushing. Even if yours has not failed, it will. They always do.

shadenfroh

It's good that you ordered the plate anyway since the thread is stripped. It's really easy to ruin it or break the plastic inside and then you have A Bad Time. And crack open your TCU, even if it's just for peace of mind.

For anyone that may need this information:

The 7 mm bolt inside the connector is torqued to just 2.5 nm / 1.84 Foot-pounds / 22 Inch-pounds. Do not overtighten or you risk having said bad time :-)

wallyp

Disconnect the battery negative cable and assure that it can't creep back into contact.
Open the SAM box inside the engine compartment near the right corner of the windshield.
Closely examine all of the wire harnesses for any trace of oil.
One of the wire harnesses will disappear down into the box and will connect to a small black plastic box (the Transmission Control Module). The TCM is not fastened to anything in the box other than the wire harness.
Pull the TCM out of the SAM. Disconnect the wire harness and snap open the TCM.
Closely examine the inside of the TCM for any traces of oil (ATF).
If there are traces of oil, clean the box and electrical board with spray contact cleaner or brake/parts cleaner. Don't use carb cleaner.
Replace everything and connect the battery cable.
You will probably need to do a few resets - they are all listed in the encyclopedia at the top of the first page on the Forum, in the light blue area, in the thread that says "...start here...".

We keep telling you this because the ATF in the TCM is a very common W220 problem, and is a very likely cause of your shifting problem. It is not clear whether or not the shop has actually checked the TCM, and the check/repair is easy enough for most owner/operators to do successfully.

Das Geld 2

Thank you everyone for the support and kind words.
I checked everything and it was clear.

I wanted to wait 2 weeks after the fix to make sure everything is good.

it was in fact the faulty speed sensor in the ecp. Upon fixing it and performing a flush the car shifts like new- silence and super quick shifts.