Mercedes-Benz Forum banner

06 c230 Remote Key Wont Lock/Unlock Doors

33K views 105 replies 9 participants last post by  vckreddy@gmail.com 
#1 ·
Hi Members,

recently registered to this forum. Thanks for all the great information you guys provide to MB owners! I recently purchased a new smart key for my 06' C230 Sport. When rec'd and tested by the dealer, the key worked fine (doors lock/unlock and trunk unlocked). The next day the key worked intermittently (for the most part didn't work). I returned to the dealer the following day and they replaced the battery, but the key still didn't work. Since then (going on week 3) I continue to try to lock/unlock using the key hoping the problem will resolve itself. Still no luck. However, just yesterday, using the key again, the car and trunk unlocked, but would not lock again. But today Still not working. I can manually lock/unlock using the push buttons on the dash/console. The key works fine starting up the engine, the auto-locks still work when driving off and auto-unlocks when stop and open the door. Additionally, pressing the key directly in front of the door sensor does to work but the red light indicator on the smartkey shines brightly when pressed. Before resorting to a diagnostic ($$$) would like some indication of possible issues/experiences causing my NEW key not to work properly???

thanks
 
#4 ·
Lock the car with the remote if you can and open the door with the metal blade key,,, does the alarm siren go off ??? if not then the siren has failed and the reason for fuse 8 to blow, this is for the long range RF locking.
 
#5 ·
Hi Members:
I have the key lock/unlock problem intermittently. It happens after every 7 or 8 times working well. It only happens after the car has been parked for a few hours, no matter if it was locked or unlocked. When it is unlocked, the key is not capable to lock it. When opening the unlocked door, the panel lights on and the kilometers numbers do not appear. In place of the numbers it shows - - - - - -. As soon as the key is turned to start the engine all the kilometers numbers are shown and the engine starts. After that , the lock/unlock system can be used again, locking and unlocking the doors for another 7 or 8 times. I went to the dealer twice and could not repeat the problem. The Stardiagnosis didn´t detect any malfunction. I already confirmed that the RF and the Infrared systems are working, as the the batteries of the two keys are good.

Paulo Kropsch
Rio de Janeiro-Brazil
 
#9 ·
No, I don't believe that will help. I think you may have an EIS problem. Or a wiring problem somewhere in the car that is causing CAN bus trouble. That's just my guess. Maybe Malcolm will have some ideas.
 
#10 ·
I did give this more thought, it is the EIS switch that has the information and detects the coding. The mileage is all CAN operated, the EIS N73 is the master of the CAN, the same bus is used for the remote locking, the only other thing in this is the front SAM, but looking very much like the EIS as SAM is unlikely to do this.
 
#11 ·
Hi rudeney and television:

I thank you for the answers. I'm seeing that the solution will not be easy to find.
I will disconnect the alarm horn, to stop calling the attention of people every time the problem happens. I intend to keep using the car to see if the problem gets worse and can be detected.
As I informed in the first post, I have been twice to the same dealer and his Stardiagnose didn't show any code. I have the impression that the technician really tried to find the problem and not only trying to get rid of a client with an old car , and not a new car recently sold by them.
Do you believe that the Stardiagnose would not detect the problems that you are thinking I can have ? In this case I should go to an other dealer.

Paulo Kropsch
 
#12 ·
SDS can pull fault codes if any are stored. I'd check the EIS and the instrument cluster (ICM). If there are no faults, then about the only way to track it down is to put a CAN bus scanner on it (a tool that is part of SDS) and watch what's going on when the problem manifests. That's going to require a very skilled technician - not just one who reads codes and swaps parts. Not all dealerships have such skilled techs.
 
#13 ·
Hi Rodney:

I will go once more to the dealer and ask him to test only the EIS and the ICM.
Have you seen this CAN bus tool ? How does it look ? I want to be sure if they have it or not.
Is this tool connected in the same plug under the dash panel, where the SDS is connected ?

Thanks Paulo Kropsch
 
#14 ·
The CANtool is a box with an LCD display on it and it has a special wiring harness that connects to the CAN bus test port in the passenger footwell. It's part of the "SDS kit" but not part of the SDS computer system that uses the OBDII port.
 
#15 ·
I have exactly the same smart keys problems with my 2004 C230, even after changing the batteries in both keys. They work well all the way until I recently sent out my car for hand washing. The engine starts easily and driving is normal. The dashboard show no other problems. Doors can be operated by the button in the dashboard. Another big problem after hand washing is that the radio now becomes very weak even in open air. I guess the radio frequency is out of order but I cannot find the antenna. Kindly let me know how I can make good the smartkeys and the radio again. Thanks. Winston.
 
#16 ·
This is Winston. Kindly note the following additions to my existing problems. When I opened the door with the mechanical key, there is no siren. Right after the hand washing, the two sliding windows could not work. They could not slide up or down. One window automtacaly slid down by itself. The window problem was resolved in a few days by themselves. Only the door and radio problems now still remain. Obviously, the hand washing had created all the problems. I would greatly appreciate any advice as to how to solve the radio frequency and other possible problem. Where can I find the antenna?
 
#17 ·
Hi Winston,

You obviously have a leak or multiple leaks somewhere or a blockage in a drain and water isn't freely running away. These are early to intermediate symptoms of a problem that won't go away and will cause a great problem and rust at some point. The reason they "fix themselves" is that the connections may eventually dry (and luckily for you) haven't shorted out.

Check rubber seals in doors for cracks, missing plugs, all around the front of the windscreen and into the engine bay for leaf matter and pooled water. Around the boot/trunk (Radio Amp is in the Truck) and under carpets etc. Smell for damp carpets. Water and damp are your greatest enemy.

One of the forum members bought a W203 last year and within three months the ECU fried because water was allowed to build up to the point that it eventually spilled over and shorted the Battery.

I think it's important to keep the car as dry as possible until you rule this out.

Hutcho
 
#18 ·
Hi Hutcho, Thanks a lot for your kind and detailed advice. I guess you are quite right and that is why I have the problems right after the car wash. I shall hurriedly do a massive clean up and drain away the possibly trapped water. Where can I find the radio amp inside the trunk? If radio amp the same as the antenna? I would very much like to locate the antenna which is not mentioned in the thick owner's manual. I guess the antenna and hence the radio frequency is the culprit for the weak radio and the malfunctioning door keys. Do you agree? Before the car washing, the radio worked very well even in the basement. Now it is hardly audible in wide open area. Thanks once again. Winston
 
#19 ·
Hi Hutcho,

By radio amp do you mean the fuse for the radio? I have lost the sheet detailing the fuses. Would you kindly check for me if the same fuse controls the radio and door keys. What fuse number and what amperage is it? The radio works though it is dim. Do you happen to know if the radio and the smart keys work via the same antenna which is not mentioned in the manual?Thanks again. Winston
 
#22 ·
Hi Winston

There's two "wells" on either side of the Truck and you access the Amp and Antenna Booster under the carpet in the right hand side one. I'm guessing that you will find water in there. The Key's operate of infra red, so I don't think the antenna is the issue with the Door Locks, but they may run on the same circuit (??)

Again the damp carpet smell should be prominent.

It is a common problem for one of the studs holding lining the inside the trunk to get lose and fall out and water leaks through it and into the sound Amp...there's a few very recent (within the last week) threads have been opened detailing the same problem, and you should have no trouble finding them.

Hutcho
 
#24 ·
Hi Hutcho,

Thanks a lot for your further information.

I spent C$120 for the car washing. All carpets were taken out for thorough cleaning, including the large piece in the trunk. It is unlikely that there are water pools because of the washing. The problems were discovered only 30 minutes after I took the car back due to the smell of the overheated fan.

Tomorrow I shall check thoroughly and let you know.

Winston
 
#25 ·
RCL (remote central locking) uses two simultaneous transmission methods for the SmartKey to send signals to the car: RF and IR. The RF interface works from a distance (say 10 meters). It is received by the antenna amplifier, which is a long black plastic strip containing electronic circuitry attached to the very top of the rear windshield, behind the headliner, and underneath the stubby antenna. The IR interface only works within 1 meter. Small sensors (black squares) on the front door handles receive the IR transmission sent from the end of the SmartKey.

Note that the RCL functions of the SmartKey require a battery in it to power the circuitry. The EIS (electronic ignition switch) communicates with the key via IR, but it uses a separate circuit inside the SmartKey unrelated to RCL. The EIS inductively powers this circuit in the SmartKey, so its battery is not used at all. It is entirely possible for a SmartKey to work in the EIS but not for RCL and vice-versa as the two functions are mostly unrelated.

A very common failure on the W203 is with the antenna amp. When this happens, radio reception will be weak (the antenna amp also provides FM signals) and the RCL function will either not work, or its range will be severely diminished.

There are three ways in which the antenna amp can fail. One is just that it dies, due to heat, vibrations, age, etc. When this happens, the only repair is to replace it which is expensive and labor-intensive (requiring removing the headliner or the glass). It can also detach from the glass, where it loses contacts with its antennae that are embedded in the windshield. This happens due to heat, vibration, and sometimes at the hands of a tech who is working on the headliner, tinting or cleaning the rear glass, etc. Some owners have reported fixing this by gently pulling down on the rear edge of the headliner to get their hands against the amp strip and then gently pressing it back against the glass on a warm day. Other times it has to be removed and re-attached.

Finally, the antenna amp can lose power. Voltage is supplied to it via fuse #8 on the rear panel in the trunk. If this fuse is blown, it's probably the easiest problem to fix. Start by replacing the fuse. If it blows again, then you have a bad ATA (alarm) siren, as it shares the circuit with the antenna amp. The siren is located behind the front passenger wheel, underneath the fender shroud. It has an internal rechargeable battery that dies with age/environment and requires the entire siren to be replaced. If you don't care to replace it immediately, you can simply unplug it - it has no other function besides sound.
 
#26 ·
Hi Hutcho and Rudeney,

I am now opening up the trunk, and have removed the carpet and the covers.

The right rear side is a spare tire while the tool kit is next to the tire. Towards the back seat is a long narrow and shallow strip with quite some wires. I don't see the two wells.

There is no trace of any water in the trunk.

How to send you pictures via this forum?

Should I remove the spare tire and the tool kit to search further?

In the front of the car, I don't see any water under the hood. It seems that water is not the culprit but all problems started within 30 minutes after hand washing the car at a cost of C$120.

The first problem is the smell of the overheated fan. Then, the windows could not slide down. Then the doors cannot be operated by the smartkey. Last is the much weaker radio signal.

I have enjoyed using the car without any problems at all before that hand washing.

I studied mechanical engineering in the university more than 60 years ago. I don't even understand what is amp if it is not ampere. Hence, it will take me time to digest the message just sent by Rudeney. He is extremely kind to explain in details those technical details.

As a university graduate in engineering, I should be able to know what Rudeney is talking about. Possibly, I have to check some technical words with the dictionary in my iPhone.

I can understand RF is radio frequency. But I can hardly understand the other abbreviations.

Rudeney has kindly sent me many sheets of fuse lists. Originally, I only have 1 sheet of fuse lists. Now there are as a many as 10 pages.

So far I can only find two fuse boxes, one at the end of the dashboard beside the driver seat, the other under the hood in front of the driver seat. I do not see any fuses or relays in the trunk or elsewhere.

How can I find the right fuses from Rudeney's sheets? Are there any other fuse boxes other than the two I mentioned above?

This 2-door 2004 C230 Kompressor is a very lovely car. It is especially good for my wife. I don't really want to scrap it.

Hence, any help you gentlemen can offer to save this lovely small car will be most gratefully appreciated.

Winston
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top