CLK430 P0715 code, stuck in limp mode (722.6)

[Popsy]

Hi Folks,

Newbie looking for some help please with my 2002 CLK430 convertible (722.6 5 speed auto) that's stuck in limp mode. My OBD II scanner returned code "P0715 - Input turbine speed sensor". CEL is also showing. I've searched a lot of threads on this issue and based on the advice have changed the following with Mercedes OEM parts/ fluids:

• ATF 134 fluid / filter / Conductor plate / 13 Pin connector socket.

The old connector was leaking slightly, so cleaned the plug with connector cleaner before fitting the new socket. I filled up with new fluid and checked the level (using the flexible dipstick I bought off ebay). This was done at 80 deg C - checked with thermal camera on gearbox sump. A friend has reset the fault code in the gearbox ECU and CEL using an Autel Maxisys scanner but as soon as I drive the car, the CEL comes back on and it's still stuck in 2nd gear and thumps hard when moving from P to R and D.

He re-scanned and it's still throwing up the P0715 code with the following message "P0266 - fault code is stored in the component 'N15/3 (Electronic Transmission Control (ETC/EGS) module)'.(P0715).

Any thoughts on where to go next with this issue would be much appreciated.
Thanks

 

[Will]

Probably best to have it plugged into a STAR machine as a starting point and see if the old codes can be cleared?

 

[Dodipops]

If you can get access to live data in the gearbox, have a look at the turbine speeds. One of them might read a crazy rpm, if so likely to be the speed plate.

 

[Popsy]

Thanks guys. I'll get a quote from my local Merc specialist to plug into star. Dodipops - when you say it could be the speed plate, is that the conductor plate with the speed sensors on it?
One thing I forgot to ask yesterday was - do you know where the transmission control module is located? I've read that fluid can wick up the cable and contaminate the TCM connectors. Might be worth a try?
Cheers

 

[grober]

Evidently in one of the footwells under a kick plate this thread says passenger side but whether this translates to RHD don't know. If the TCM is contaminated by ATF wicking up the cable you should really renew the connection cable as it may just re-contaminate a cleaned TCM
Instructional: Cleaning the TCM - Transmission Control Module - MBWorld.org Forums

 

[Popsy]

Many thanks grober. I did look for it yesterday but couldn't see any obvious signs of an ECU in the foot wells. I'll check again tonight.

 

[Dodipops]

Yes the conductor/speed plate. TCM in passenger footwell clipped to the rear of the metal foot rest plate under the carpet.

 

[Popsy]

So, I checked the TCM. The cable was slightly damp with fluid and there was some on a couple of the pins when I removed the connectors, but nothing major. No sign of any on the PCB. Everything was cleaned with a good spray of connector cleaner and reassembled.
Unfortunately, it hasn't resolved the issue. I'm going to hook it up to my mate's Maxisys scanner on Friday to try and check the live data.
Thanks for the suggestions so far.

 

[Popsy]

Hi Guys. A quick update on the situation. Took it to my mate who erased the CEL and P0715 code in the TCM but couldn't read any live data relating to turbine speeds. Drove home and the CEL didn't comeback on but still stuck in 2nd gear. I rang the local Merc dealer who wants £108 an hour to diagnose and was told "best to allow up to 3 hrs" - over £300 potentially. Apparently I get maximum discount due to the age of the car - they normally charge £150 /hr for newer cars!!!! Needless to say I'll leave that as a last resort.

Spoke to the local specialist who suggested that the code may need to be reset in the TCM using the STAR system. I'm not sure why that would be different to the code reset using the Maxisys but running out of options now. They charge a more reasonable £72 / hr.

Before I go down that route though, I know it's a long shot, but does anyone know if there's someone around the Plymouth area who may have a diagnostic scanner that can read the full set of live data and perhaps be able to fully reset the tranny code? I'm wondering if the Maxisys is advanced enough.

Thanks again for all the advice so far

 

[alabbasi]

If the plug is leaking, fluid can work up the wires and into the TCU so remove that and check it. If it's covered in oil , it will act out.

 

[Popsy]

Cheers for the suggestion alabbasi. I did remind some fluid wicking up the cable into the TCM, but only a few drops. I cleaned it up with connector spray but doesn't seem to have helped.

 

[Popsy]

Hi all, just a quick update on the gearbox error. Took it to the local specialist yesterday - reset the codes using the STAR system and it's now smooth as silk. Apparently the transmission error codes can't be reset through the under-dash OBD connector. It has to be done via a connector under the bonnet.

Very happy to be back on the road and thanks again for all your suggestions.