Ellioth Zombye

Hi, like I said before Im a new Mercedes owner and still learning how it works, the problem that I'm starting to have is that the car sometimes wont crank, it takes two or three times to turn on. I check the battery and the alternator using the climate control menu and they are okay, just want to know before get in the issue that my car wont crank at all, what are my options ( fuses or parts ) that I need to check or change, I know this issue has been posted before but couldn't understand, so please be patient and guide me step by step,

Thanks for your help! BTW if anyone have a question about cellphones I'm a technician and would like to offer my little knowledge and help you, I know this is not the right forum but no one knows when you need it.

cindyclk

Have you changed the battery in the key?

Ellioth Zombye

No I haven't, But that is a good start. will post results ...

Serndipity

Ellioth........in order for your car to start, the the drive authorization system (DAS) must be working properly, which is explained in great detail, in the above document.

Unfortunately, diagnosing, trouble shooting and repair of the DAS system is not a DIY endeavor, as it requires specialized knowledge and equipment (e.g. MB STAR diagnostic software, breakout boxes etc.).

Note that as explained above, the batteries in your FOB (i.e. key), are not used to start the car (e.g. once the vehicle has been authorized, the power to run all the necessary modules, is supplied by the primary vehicle battery).

Assuming that the DAS system components are working properly, following are some DIY suggestions to try.

The electrical modules are very sensitive to the vehicle battery condition. If the battery can not deliver a minimum of 11 volts on start up, the modules may not work properly. Using the HVAC module data is not a very good way to see if your vehicle battery is capable of supplying the required power to start the car (e.g. because when the vehicle is running, the alternator is helping the battery). There have been many no starts due to a weak battery not being able to readily supply 11 volts to the system and/or corrosion at the battery contacts.

Try using your spare key to start the car, in order to rule out a DAS communication issue, when the key is inserted. into the electronic ignition control module (N73). If that corrects the no crank issue, you may be able to DIY repair the faulty FOB (e.g. re-soldering the inductive coil).

If the DAS system is working properly, the engine control module (ECM) should activate the relay that supplies the necessary high power to the starting solenoid/motor that cranks the engine. You haven't supplied you location, but in North America, the fuse and relay for the starter motor are located in the passenger side fuse box. The relay contacts, or fuse contacts, may have become pitted due to switching the high current required by the starter motor. The relay is a multi-purpose type, used in many other circuits (e.g. power roof pump, fuel pump etc.) and only a $8 replacement part.

Lastly, the brushes in the starter motor may be wearing out or making poor contact. If so, hitting the motor with a hammer or 2x4 may turn a no crank into a crank.

Good DIY troubleshooting, my friend.

cindyclk

Serndipity is correct above...as he says in second paragraph...check key to see if it's communicating...start simple

Ellioth Zombye

Thanks for your help, I've been using the spare key, the black plastic key and It works just fine, even notice than the car recognized faster than the smart key, no problems so far and the car start on the first try , but the smart key seems to be having problems: yesterday the car didn't want to release they key from the ignition, after like 10 sec finally let it go , but according to the previous owner records that he gave me when I purchased the car, he purchased a key and a master key, he paid 291.22 us dollars,( i have the receive) but I have notice that my key don't have the red led when you press they key and don't have the infrared on the top that you can see with your camera is apparently this key is made by panasonic , does key usually got bad so fast? or maybe he just got a bad one, neither the driver door unlock or the trunk, and the mechanic key only unlock the doors but wont lock them.

Again thanks for your help

cindyclk

It sounds like the smart key is the problem...maybe got a non oem from somewhere

Ellioth Zombye

Yeah thats what Im thinking I will post a pic so you can be aware of this

Serndipity

Ellioth............The CLK came with 3 keys, which included (2) main keys with integrated radio frequency and infrared remote control buttons to operate the central locking system and (1) reserve key which is much thinner because it does not have an internal battery and the remote control features, but can be used start the vehicle. Also the mechanical keys that were also included, work only in the driver's side door, the trunk and glove box locks.

From what you have explained, It appears that you have the MB reserve key (e.g. that originally came with your CLK), which will reliably start your car, but your main key is a clone (e.g. not the original MB key) that will sometimes start your car.

That's actually very good news, as it pretty much indicates that the problem is with your cloned main key and not with the with the other DAS 3 system components shown in post #4, which otherwise would be very expensive to diagnose, troubleshoot and repair.

The only way to get a genuine replacement main key is from a MB dealership, which will cost around $400. The dealership will require owner verification and use a specialized process and equipment to authenticate the key to your specific vehicle VIN.

But before you purchase a replacement key, your cloned key definitely has a different case, which may or may not contain a MB genuine printed circuit board, here are a couple of potential inexpensive DIY repair suggestions.

As shown in the DAS 3 diagram, when the key in inserted in to the N73 Ignition switch control module, authorization to start occurs via 2 way infrared light communication. It is possible that the end of the Panasonic case, when inserted into N73, may be obstructing the necessary IR signaling. If so, as further detailed in this YouTube video, a proper case can inexpensively be sourced.


The next video has a lot of information pertaining to how to remove the printed circuit board from inside the main key etc.. As previously mentioned, the power to run the mobilization process occurs via electro-magnetism when the key is inserted into N73. Basically, the coil inside the key, when inserted into N73, produces sufficient power to read the authentication values in the key's ePROM. As you likely know, when regulations removed the lead from solder, the long term reliability of soldered connections took a nose dive. I recall watching a video where re-flowing the coil connections, corrected a no start problem.

Ellioth Zombye

Thanks for your help, this is actually what I have


still, no hole for the infrared

Again, thanks for taking your time