Amg_boy

Hi all,

I have been experiencing a gearbox issue with my 2008 C63 where it used to go into limp mode with a noticeable "Thud" and the gear **** indicator (PDRN) square on the dash would disappear.
Afterwards, the car feels like its stuck on a high gear as it struggles to move off. Then, after the panic of first few times I got used to ignition cycling it and it would go away.

I eventually got the codes read and the main one seemed to be y3/8n4 Fully integrated transmission control unit is defective. Research told me this was a fault with the processor unit on the conductor plate.
Also I had the 1405 code : No CAN message was received from control unit Transmission.

So I decided it was time to replace the conductor plate. I ordered a replacement (refurbished, pre-coded) conductor plate and went through what felt like brain surgery to carefully take out valve body and replaced the Conductor plate with new bolts and same solenoids.

I made sure oil was topped as per the procedure and when I started up i noticed the square around P for a brief moment and it went missing. The car does change from PDRN but with a thud each time and I havent been brave to actually drive it. Something is wrong.

The error codes I have is below right now that will not clear :

1405 : Communication with control unit "Transmission" has a malfunction.
U1108 : No CAN message was recieved from control uni "Engine control system"
U0155 : CAN communication with control unit "A1 (instrument cluster)" has a malfunction
U0415 : The CAN signals sent from control Unit "Traction System" are incomplete
U0141 : CAN communication with control unit "N73 (electronic ignition lock control unit)" has a malfunction
U0126 : CAN communication with control unit "N80 (steering column tube module control unit)" has a malfunction
U0164 : CAN communication with control unit "Air Conditioning" has a malfunction
U0121 : CAN communication with the traction system has a malfunction
U0100 : No CAN message was received from control unit "Engine Control System"
U0103 : No CAN message was received from control unit "N15/5 (Electronic selector lever module control unit)"

Few things to note : The battery was disconnected during the replacement process, Only the conductor plate was replaced (pre programmed based on VIN), solenoids not changed,

Any help or guidance would be much appreciated rather than resorting to towing to a specialist or dealers. I currently have the car on a drive on ramp (which I optimistically bought thinking this repair would justify the spend )

Thank you very much in advance for anyone even remotely attempting to help

JettaRed

iTrader: (1)

I don't know for certain, but I think there is more to configuring the conductor plate than "pre-programming" it based on the VIN. I could be wrong. When I had problems with the conductor plate in my 7G tranny in my 2004 SL500, I sent it to Circuit Board Medics. I had broken off the connector, so they jury-rigged something to access the existing control module and transfer all the coding to a replacement conductor plate. If my VIN was all they needed, then they would not have needed the old conductor plate to transfer codes to a new device.

Where did you get the replacement conduction plate from? Do you still have the old conductor plate? You may want to contact www.circuitboardmedics.com and talk to them about your issue. Or contact @BenzNinja who may be able to help, as well.

Adi-Benz

It could be the valve body instead.

We're there any metal fragments in transmission pan magnets when removed?

Also you probably don't need them but I have good working valve body + conductor plate for sale but they'd need to be coded to your car as mentioned.

Odd Piggy

Yes. The VIN identifies the component to the DAS to enable starting and driving the car. There is a pre-adaptation process for the conductor plate if the memory isn’t or can’t be transferred from the old to the new one.

But the numerous comms codes that won’t clear make me think there is a deeper issue. It looks like they are across multiple CAN networks. I think there are 7. Transmission and air conditioning are definitely on different networks. Maybe a front SAM or central gateway issue???

Amg_boy

Thank you I have gotten InTouch with circuit board medics to hear what they have to say about this. I am really hoping it doesn't need further transfer of programs. Otherwise the eBay company I got it from gave me wrong instructions.

Also I have sent my old conductor plate to ECU testing to see what they will diagnose. Usually with a Y3/8n4 fault they say it's not repairable.

Thank you

Amg_boy

Nothing excessive that I noticed. There was sludge around the magnets but not clear signs of metal swarf.

Oh right that's good to know. Could you please send me a private message with what price you are expecting for the whole unit please ?

Amg_boy

Ok thanks, what puzzles me is that I didn't see these error codes with the original conductor plate. Ive only started seeing these errors since I swapped it with the replacement conductor plate. So it's a little confusing.

I really hope it's not a symptom of a completely different issue.

I have sent the original conductor plate to ECU-testing to diagnose. If they don't find an issue then you could be right.

trigital

Indeed, there is no "pre-programmed" plug& play 7G TCU. It will need to be Teach-in with the drive authorization system of the car ( DAS ) and with the gearshift mechanism.

Amg_boy

This is very interesting because the response from the company that supplied the conductor plate insisted that they have tested the unit and that it should be plug & play. Since this is a regular product they sell im not sure if they have made a mistake or usually sell to garages who then complete the teaching process independently.

JettaRed

iTrader: (1)

That is a possibility. However, there is no "plug-n-play" with what is considered a theft-deterrent item.

If the parts @Adi-Benz has does not match, I also have a conductor plate and valve body from my 2004 SL500 7G that may fit. Just compare part numbers.

trigital

Did you send your TCU as a replacement?

Odd Piggy

You disconnected the battery, so maybe the errors are just a result of disconnecting and reconnecting it. I think most of these have a fourfold reporting redundancy (powertrain is threefold), so the ECU will have to see four failure free starts to drop the codes. Don’t panic (yet) because it may be there’s no issue with the networks.