'97 C230, @ 144K miles, threw CE light & went into limp-home mode, without warning... used primarily on the interstate, vehicle was asymptomatic before hand.

Dealer advised transmission had failed and a remanufactured unit would be required. Transmission oil and filter had never been changed.

Removed vehicle from dealer and checked fault codes:

ME.2
P0715 - read ETC DTC memory
P0720 - read ETC DTC memory

ETC.6
013 - speed sensor n3 (Y3/611)
109 - occasionally speed sensor n3 (Y3/611)

Found fluid in AT wiring harness plug adapter; installed new style adapter (140 270 02 50). Renewed fluid and filter, installed pan magnet. Drained fluid, although discolored, was free of metallic debris; some fine grey-colored particles were present in pan.

Now, 4,500 miles later limp-home mode has recurred, along with the same DTCs. Vehicle runs and shifts flawlessly, however, when codes are cleared. The interior of the new wiring harness plug adapter is dry.

The speed sensor in question is integral with the electric valve control unit (electro-hydraulic control unit; 140 270 05 61). A new unit is devoid of the six solenoid valves, however; installation requires transfer of the existing valves to the new unit.

A reman'ed valve body (140 270 06 06 88), although several $100 more, comes with a new electric valve control unit and solenoid valves.


Given the vehicle's mileage, would it better to install a reman'ed valve body, or would renewal of the electric valve control unit be sufficient to correct the speed sensor problem?

I would just replace the conductor plate with the speed sensors. It is a common problem and a simple repair.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Hi,

I have a 97 c230. I believe I am in electrical limp mode. I pulled a p0715 and p0720 with my generic scanner. I can clear the codes but when the vehicle is started they come right back (never leaving limp mode). I did some trouble shooting and with mitchels repair manual and all data, The results prove the actuator plate is bad (The plastic board on the valve body), Well this is when I purchased the plate and changed it, with the original shift solonoids... No change, same codes and still in lim-mode,,can anyone help.....

To Frank: You can not reset the electrical limp mode with a generic scanner or any other "tricks" like removing the battery etc.
You will need a Mercedes HHT or a Snap On scanner with the appropriate cartridge and personality key.
A friendly dealer or an indy with the right equipment might be willing to re-set the limp mode for you

To JGL:
Did you ever check the Transmission Control Unit to see if there is oil in it.
If so, you can remove it, clean the PCB with a circuit board cleaning spray.

Is the TCU in my model the one under the passenger floor or the one under the hood right rear...thanks Also , I have access to a snap on 2500, however the only keys i dont have are 19 and 20.BUM LUCK. Are there any others I can use.... Or suggestions on obtaining the correct key.

thanks
Frank

you need the S20 key to communicate with the Transmission control unit.
They are around $15 from your local Snap On dealer

Do you have any advise or procedure I can follow for clearing the TCU codes with the proper scanner and personality key...

It is pretty self explanatory once you have the MT2500 hooked up to the 38 pin connector. You will have to select the system you want to communicate with. In your case it is the electronic transmission control. Select "all transmission data" and scroll through the line items untill you find "limp Mode".

is the 38 pin connector the data link connector under the hood and or can i do it using the connector that is normally used for obd2. I truly appreciate this.. Like I said I have access to an mt2500 but I need to buy evrything else.. I understand i need the s20 and the euro cartridge.. is their any other special connector I need?

Frank

I am sure that you can not use the OBD connector to reset limp mode. You need to the 38 pin round connector under the hood. You will need a Mercedes Cartridge up to and including the model year of your car. The generic Euro cartridge is only used to connect to your cars obd, you don;t need that.
Besides the cartridge you need the cable that connects to the 38 pin connector (MB-1 connector pn MT2500-62). It has the slot for the personality key.

Thanks Buddy. Will post my outcome. I plan on keeping my car until it spits the body off. Its a great little car, just need to get smart on some things.

thanks ace. i used a solus to clear the code, back on the road, will post pix soon, going fishing tomorrow. thanks again..