LOB

Hi,

I have a clk 270 cdi 2004 and recently I have some issues...

1. Sometimes when I unlock the car with remote key it unlocks and 2 sec after locks (I note that this happens first time in the morning or when is stopped for a while)

2. During run sometimes it unlocks (or locks) the doors and turn signals blinks two or three times

3. During run the four turn signals start flashing and I have to press the button to stop it.

Somebody could help me??

Rudeney

My guess is that you have a defective rear SAM.

LOB

Thanks Rudeney for your reply

Any idea how I check if rear SAM is defective? I diagnosed with star DAS and hadn't any error at rear SAM...

Rudeney

Looking at the block diagrams, that's the only electronic part in common. Well, the EIS is involved, too, but I doubt it's that. The SAMs seem to be prone to failure when are voltage fluctuations. Speaking of which, if your battery and/or alternator are bad, you can have all sorts of electrical gremlins. What's the resting and running voltage on the system?

LOB

My battery is brand new...
Some DTC erros from driver door. Headrest (seat) only goes up when I try do put it down button sometimes doesn't work

LOB

Almost two years pass and the problems continue.
But since now I'm using the car everyday this problems are driving me crazy...

More problems appear meanwhile... Dashboard sometimes blinks all lights and then I get the error replace key. I tried to use the 2nd key and the problem continues.

The unlock and lock during running is getting worst.

Will try to do a video.

DanielFD

Rodney is probably right, looks like its most probably your rear sam. On my old c class the rear license plate lights would turn on for 5 seconds then off for another 5 then the cycle repeats. Changed the rear sam, problem gone. Also checkout some of the threads on the site again. there is a fix for the headrest thats simple and theoretically involves no money.

LOB

How can I be sure that's a defective SAM before buying one?

Rudeney

My suggestion is to always get a proper diagnosis. The dealer's SDS (Star Diagnosis System) can pull codes from system (like the SAMs) that generic OBDII scanner cannot. If you can;t get the codes, then you are resigned to "throwing parts at it".

LOB

I have a generic obd scanner but I can access to almost all modules of the car, including the rear SAM... It had some errors that I could delete but later on I will connect again to check if they come back.
Most of the errors I have registered are related with OCP module. Intermittent connection failure... And the thing is, I can't access to the OCP module.
Some time ago I tried with a star das and wasn't possible to access it too, so we assumed that the problem was that module. But after that I tried with two other ocp modules and the problem persists...
Thanks

DanielFD

A generic OBD scanner cant access modules specific to our car such as the REAR SAM or TCU. You will need STAR. As with the OCP module, I'm not sure about this, but i'm guessing the rear SAM is the module that talks to the OCP module.

LOB

I had a misspelling error on my last post (edited now). What I wanted to say is that I CAN access the REAR SAM with my obd interface as well the TCU... If is the rear sam that talks with OCP maybe it's indeed a defective rear sam...

DanielFD

Well i'm guessing at this point. I dont know much about how the system works. But what puzzles me is how your generic OBDII scanner can access the rear sam and tcu! what brand of OBDII reader are you using? I once used a Launch X431 Pad and it was able to access all the modules except front sam and read sam and ocp, and thats a 1000$+ scanner.

LOB

I'm using Autocom CDP 2013.3
Later on I can upload some screenshots...

DanielFD

Interesting! Well what errors do you get on the rear sam? anything on the EIS?

LOB

Error on REAR SAM:
B1090 (Permanent): Fault in CAN communication with control unit OCP .If fault code occurs with no complaint reported and no malfunctions, erase fault memory and perform a
function check

Error on FRONT SAM:
B1031 (Permanent): Control module OCP is not transmitting any data.If fault code occurs with no complaint reported and no malfunctions, erase fault memory and perform a
function check

It seams that any module could connect with OCP.

No errors related with EIS

DanielFD

Thats weird. Logically I'd say your OCP Module is shot. But you already tried to fit in a different unit. After you fitted the unit did you reset the codes? Maybe thats the reason it didn't work? Btw the key function problems you were having are managed by the rear sam. So this is all a bit weird!

LOB

I already tried with two difference OCP modules and the problem remains. And yes, after fitting a new one I clear all the erros...

DanielFD

No idea really, if i were you i'd search for some articles or pdf files online about how the CANBUS system communicates. Maybe its something as simple as a break in a wire somewhere?

Rudeney

Check the pins on the wiring harness to make sure nothing is bent or dislodged. Otherwise, it sounds like you may need to trace the CAN bus wiring. It will be a brown wire with a colored tracer. Oh, one other thing to check - there is a CAN bus junction under the driver's door sill, inside the plastic wiring raceway. You can't miss it - a block with lots of brown wires in it. Make sure it's not corroded. Water can get in there and oxidize the wiring.

LOB

Thanks Rudeney for the tip, I will check it. The pins on the wiring harness you refer are the ones that connect the ocp module, right?

Thanks DanielFD too.

LOB

Meanwhile I could record the problem with my phone

Rudeney

I wonder if this is an issue with the key losing communication with the EIS? Here's an interesting thread:

http://www.benzworld.org/forums/w203...is-issues.html

LOB

I was already reading that thread and was my first thought (the key or EIS) but I don't have any error related to the EIS and I have the same behavior with both keys

Rudeney

I believe this is a CAN bus issue. You could have a bad connection, or it could be a device on the bus that is spewing "trash" on the network and confusing the other devices. This is going to be very difficult to find. SDS has an optional CAN bus "sniffer", but honestly, few techs at the dealers know how to use it. I am not aware of any aftermarket devices that will do this, but maybe there is something out there.

One easy thing I can tell you to check is the main CAN bus terminal. It's located under the driver side door sill. Water leaks can infiltrate this and cause corrosion. Steps 1-4 in this documentation will get you there:

http://www.mods4cars.com/sms/db/smar...all_clk/en.php