Approx location of white box in trunk

Internals of said white box - notice problems

Mystery black box possible immobiliser buried behind dash on passenger side

No signs of dealer fitted alarm in footwell

What the manual says about key

 

Here is my video taken today of what it is doing

Failure isn't an option for me here! I have invested hundreds of hours work on this coupe to restore it and cannot let it die due to a key fob issue! I will get to the bottom of it one way or another I'm sure it's just how long and costly it takes to get there. Some example pics of the work done before this-

Engine seized as it came to me

Restored replacement engine going back in

It was running amazing and with such low miles it's in really good condition!

 

I have my own Star setup and plugged it in just now. Only one code of interest-

There are also some limited actuations available. Such as

Test red led - pass
Test green led- pass
Lock and unlock car - this worked too. Central locking operates and the green or red lamp operates just as if I did use the fob.... but still wont start even when unlocked via actuation in DAS.

 

Googling the number on the black box indicates it is the immo device.
I posted service bulletins on the DAS2 and DASx systems a few weeks ago. They describe the systems, and troubleshooting them. Do a search here, and you should find them.

Jon

 

Here's a link to the post with the service bulletins.

Official Mercedes Drive Authorization System (DAS)...

Periodically, people have trouble with the MY 1996 and later cars DAS2 or DASx and transponder keys with DASx. Information on these systems can be very hard to find. There is really no data in Startekinfo about it. However, Mercedes did provide their service techs info on it. Attached are...

www.benzworld.org

Jon

 

Thank you for the replies and that PDF! Great information to have and it will come in useful. I do have a very smart friend who is an automotive locksmith. I sent him photos and info on this today and his intial opinion, having never worked on one of these is that the rear box is a receiver more than likely and should not require coding. He thinks the black box contains the key information and coding. And if MB no longer offer the keys I can give him the black box and another W140 key and he can manually flash the key to suit. (Something like that I dont fully follow this stuff!)

will study it much more but at first read it appears the ECU also ties into this system. I do wonder could I try to locate and install an earlier production W140 500 LH Engine ECU for grins?

 

The white box is the antitheft control module.

Jon

 

The bit I find most interesting about the PDF 80-6 is the suggestion that a resistor plug is used in the CAN bus and needs to be removed if installing a newer ECU and therefore equiping the car with DAS2.

Thus, I wonder if installing an older engine ECU coupled with figuring out a resistor to go back into that CAN plug might over-ride and do away with the DAS immobiliser?

 

The PDFs describe the US systems. AFAIK we never got DAS with an LH injection system. I have a 95 S600 coupe, and it does not have DAS. It has a trivial antitheft starter interlock between the IR locking system, and the PSE. It's fairly easily defeated.
We got DAS in 96 with the later injection system.
How your LH injection interfaces is a mystery to me.
If all else fails, you may want to contact the people that make the Julie immo defeat systems. They may be able to help.

Jon

 

I have been doing more testing on this coupe. I do not believe the key fob is at fault here. It was not dropped, damaged or put through washing machine etc! And my phone camera shows it is putting out a good IR signal and Red LED flashing after 2 seconds too-

I also used Star in order to test the locking system. It can be seen that the Red and Green LEDs + locking system is fully functioning via actuation in Star.

So the question remains why is the car suddenly ignoring it's key fob?? The white box in the boot is what I want to replace next. It shows online as a the "Anti Theft module". And this is the part I found the blown components inside.

My Auto locksmith has not seen this particular unit before but believes is should not require coding and may well act as a IR receiver. Which relays on the IR fob code to the rest of the system. My hopes are pinned on this unit being the current problem. It should not require coding -

My Auto locksmith and from what I have seen online indicates the black box burried behind the dash with a 210 part number IS the immobilser unit and contains information on the Key Fob of the car. That unit would require programming for sure. But for right now I am awaiting these parts to arrive:

2x White boxes for the boot for testing purposes and of course replace the blown original unit
1x additional good used tested key fob (My locksmith said if I give him my black box + a good used key he can code it together for me)
1x black immob box for the dash. However my understanding is changing this unit will require box programming of keys to suit same AND virginizing the engine ECU. A road I won't go down until everything else is exhausted.

What about the IR receiver in the door habdle? (I believe this is what my coupe has - not in the mirror) Can these sudeenly die too or have dry solder joints?

Again guys - the issue appears like the car suddenly no longer can "see" it's own key fob which to the best of my knowledge the key fob should be OK.

@MAVA - do you have any suggestions? I have been researching this all weekend and have a basic understanding of how this system works - and that unfortunately my coupe is an oddball earlier system but there should be no reason why this cannnot be fixed. Feedback and suggestions would be much appreciated!

 

@MAVA - do you have any suggestions? I have been researching this all weekend and have a basic understanding of how this system works - and that unfortunately my coupe is an oddball earlier system but there should be no reason why this cannnot be fixed. Feedback and suggestions would be much appreciated!

JC,

Jon answered the thread very well, so I did not chime-in...

Since all these cars are restoration projects at many levels, the other option to have a "keyfob" is you got to be first to arrive at the self-serve-junk yards to get the key(s)/ key-fob(s). One can transplant of similar years, or in your case I think anything under 1996, but I think 94-96 should be okay to use from S280 - S600 as the module you oppened up can be swapped out. You will need to the key element from your FOB, or have bare key made for the FOB only.

My buddy who died just 8 months ago had just proven that right before he died as his V12 coupe did not have a FOB for the car. He had found six keys and pulled six modules, and tried them all on his car, and they all worked, so I suggest you do the same. It is a lot of grunt-work to be first there. Bring coin batteries, and test the fob on your smart phone to qualify the signal from the fob is transmitted by watching it on the screen, yet you may have to video it to see the flash of light.

I do not have any, and my buddies stuff all got thrown out. Read this thread:

MAVA has not been on the forum, but my leather seat...

Yea MAVA has not been on the forum. School has been kicking my butt, but life has been a little unfair too as I have lost some my commodities of life. I'm hanging on is all that matters, and school is my priorty. The rest is optional. My stuff is in storage I visit it a few times a year. Joe...

www.benzworld.org

I know this works. This is tedious option as it is like every ten cars that has a fob that one is able to find.


Martin

 

Not sure why it wouldn’t recognize the key fob, but I can tell you where the immobilizer relay is if you want to just get the car started. And of course check if the relay is good in the first place.
it is a standard looking silver ice cube relay by itself taped or zip tied up under the dash behind the glove box. You need to jump the two purple heavy gauge wires to bypass it.
normally the anti theft module in the trunk sends signal to this relay.

 

OK it is page 29 which describes my coupe system perfectly with the one exception that the sensor is in the doors and not in the rear view mirror if I recall correctly. (Too many 140s here!)

The doc attached is a great help- It does flag up that If this white box in the trunk is the N54 module then it would require replacing to VIN also!! I did have a backup plan there whereby I have 2X replacement matching part number white modules coming. And new capacitors.

So it looks like I'll have to carefully de solder the damaged parts from my original N54, take the parts from one good donor module and try that.

The issue is my locksmith has never worked with the N54 in trunk before. (If that's what it is!) Thus he could readily take care of the key and black immob but not any programming of this white module.



I also cant see that module in Star but that makes sense since your PDF states that if the car is locked it stops access to it. I got worse case scenario here whereby it crapped itself whilst locked.

Srill digesting all of this but the focus is on that blown part.

EDIT, sorry guys a google shows N54 is the black box - Phew!! I'll keep digesting all of this and compiling all information and share it when I have it figured out properly. White box might still also have codes and require repairing.

 

My LH ECU

 

Their docs all show available and instructions for newer ECUs such as ME etc but nothing for the older LH injection module.

This is indeed what confuses me about the documents you posted. Your car is pre-facelift. The immobilizer and DAS discussed apply to MY '96+ (in the US, anything produced in July or after in 1995 will be MY 96).
Europe does things differently, but is there a chance that the white-box is an add-on? Dealer or PO installed.

The very early cars are exempt from all of these issues and one can very easily disable the factory system in favor of an aftermarket remotes. The moderator Merc-S600 has posted nice pictures and how-to.

Is this something you and your locksmith could do for your 1995-built car? Will be much cheaper than trying to source rare OE parts.

Good luck.

 

Those parts are all OE. Apparently they added DAS much earlier in the UK than the US. Everything I've seen about DAS has been for the US market, and all for 96 and later. Kind of like the US getting OBD2 in 96 for engine parameters, but other markets didn't get it till much later.

Jon

 

Those parts are all OE.

Thanks for the clarification. I can see that they have MB p/n's. But there is still a possibility that they are added later.
You installed factory OE Xenons in your 1994 coupe for example. If the next owner does not know that and looks up the manuals, similar questions about what and how can arise.

 

I'd probably try an American ECU as they do not contain VIN-locked chip, and then you can eliminate that DAS module. Then worry about key-fob module in the trunk.

The earlier cars have the eprom on a socket in the ECU, yet the later cars are soldered. The eprom may contain the vin of the car. If you remove the eprom, get a PLCC remover tool as doing it with a small technician screw driver may split the eprom socket and break it.

Technically you cannot start the car? I would worry about the convience of the key-fob later. My buddy who died did not have key-fobs for none of his three-w140's, so you can live without a fob.

I'd give that a try..

Martin

 

1992 old LH module (Pre DAS)

 

VS my 04/1995 production LH Coupe 140 ECU:

Notice the difference!! Yep 8 leg Immob chip in there. This is absolute evidence that this is factory setup and late LH systems did have a DAS2 immob setup.

Had a long chat with my locksmith. He doesn't like emulators and that's only a last resort.

After 1 hour of talking he is super knowledgeable on MBs and will have several plans of attack for me if the white box in boot doesn't get it running.

Learned alot of stuff and again, I am compiling this info and will share it at a later date to assist others.

 

Our one button Key-Fob ECMs do not look like that. Interesting that one looks up the B58253 memory chip made by the American company in Arizona, USA call Microchip, and all the searches point to UK searches, and the B58253 is the same as 24C02 Memory chip very common here.

Technically one can clone one and replace the bad one with a new one.

Martin

 

Our one button Key-Fob ECMs do not look like that. Interesting that one looks up the B58253 memory chip made by the American company in Arizona, USA call Microchip, and all the searches point to UK searches, and the B58253 is the same as 24C02 Memory chip very common here.

Technically one can clone one and replace the bad one with a new one.

Martin

The Chip isnt bad it just isnt unlock via IR and therefore has no start authorisation in live data.

I have since tried white box in trunk - no difference.

Also tried another working IR mirror from my S320 no difference.

Also got a locksmith to code a key to another IR unit, virginised my Engine ECU and tried that - no difference either. So it is NOT the key or the N54 module at fault here.

I did test the wiring plug on the rearview mirror since that takes the Fob signal in and forwards to the IR N54 module. No battery power observed. Strange but then I need a wiring diagram that reflects this darn system in my coupe first.

All the info is here folks but it appears no one knows much about these particular systems. I will find the fault eventually. Just now my theroy is voltage drop somewhere in the alarm system. A corroded plug or similar. The rear fuse box is suspect and I will be replacing it with a nice used one soon. Just loosening the mounting bolts of the rear fusebox changed the behaviour of the mad LED lights - but the fob still not working. Although the PSE pump is working via Star I still do want to test another one in the car too.

 

Decent enough DOC here which shows the N54 module behind dash in later cars. Mine is super early to have it from the factory.

 

JC,

The diagrams are here:

StarFinder

How to see the diagrams:

1999 s420 combination relay (N10) wiring diagram?

My combination relay just went out, and when trying to install the new one I accidentally released all the pins in the wiring harness (photo attached). Does anyone have a wiring diagram or can someone with the same car share a photo with the configuration of the pins? Thank you!

www.benzworld.org

How to read them:

Electrical Diagram Help

I can't find a legend for the STAR Service manual ETM wiring diagrams to help me interpret the symbols. Is there someplace with a complete legend? For example, in the picture below What do the triangles circled in pink mean when they point towards or away from a thing? Where can I find out...

www.benzworld.org

You have seen this too:

STAR TekInfo

My take is this is it DOES NOT make a difference on our American cars if the key fob works or not. The key can override those features no mater the version of system.

Your PSE comunication to key fob module is important, and should see that those signal are sent and received because that can cause a no-start condition.

These diagrams not accurate around that area of key and security. One has to kinda reverse-engineer the wiring as I found inconsistencys. I had found the IR sensors not correctly documented..

Martin

 

Thanks for that info Martin! I found the correct diagram eventually.

I got somewhere with the coupe!! Swapped over the working S320 N54 and Key fob into the coupe and low and behold now it does lock and unlock by key fob! So somehow both the original N54 in the coupe and the Ebay one I bought are faulty! (And or the key fob(s) my locksmith will investigate further)

But its not all good news. The virginised ECU won't start up even though the coupe IS now unlocking by IR. Havent hooked up Star but I bet it needs the ECU virginising looking at again. Ah well - some major progress knowing that it is solely within the black N54 box and / or key that requires replacing and the ECU will get figured out.

He saved the LH status before we did anything. Locksmith wants to create a replacement key for the S500's original N54 and that would allow the engine to start if it was my key fob at fault.

Such a session! But again, progress is finally being made and it will get sorted after some more faffing around. Glad some life is back in the coupe at least and I dont have to start taking into all the wiring harnesses etc

 

My MB dealer is still closed due to Covid. I'll try emailing my parts dude to see If they can price and order a new N54 for my coupe. Car will need towed down etc what a PITA but want this resolved sooner than later

 

JC,

If your key guy has enough knowledge, I would perform a Hex-Read of the module with each of the B58253 and compare the hex file of each, yet that is a process most embedded developers do. I sure do it too when I'm writing code.

Technically one can re-write/clone/erase a B58253 which is a 24C02 serial memory chip. Their are many web sites on how to do it.

Martin

 

JC,

If your key guy has enough knowledge, I would perform a Hex-Read of the module with each of the B58253 and compare the hex file of each, yet that is a process most embedded developers do. I sure do it too when I'm writing code.

Technically one can re-write/clone/erase a B58253 which is a 24C02 serial memory chip. Their are many web sites on how to do it.

Martin

Its a little (lot) more complex than this Martin. Note that the N54 information is not in the B58253 chip. (Like it is within the Key Fob and Engine ECU) The N54 has a much larger Motorola chip which contains the coding and VIN Data etc. This has to be de-soldered and key information generated from it.

And the Motorola chips usually have partitions in them which are very hard to clone, sometimes wont even let you write over it. So that is a no go to copy a N54. What we are considering is lifting my N54 chip onto another N54 board for testing.

But first, we want to make a key now for my S500's original N54 unit and I will go home to test it. We will also put the LH ECU back to how it was before since it will then tie back to it's N54 chip as before.

 

From testing today and to assist others please note some of my following observations:

TESTING:

• You can take a good used N54 with Key fob over to another car for testing purposes. This will allow you to lock and unlock the car (If there is nothing wrong with the chassis wiring & IR Sensors that is) BUT it will NOT allow start authorisation unless your engine ECU has been correctly virginized or you have it's matching Engine ECU.
• In addition, when you have another N54 in a car and you connect with Star you have to turn the ignition on. The N54 module will then check with the engine ECU if it is a match and if not, will lock the N54 out of star. You cannot see fault codes or anything at all. Nor will it appear on the quick test - nada.
• Star does have actuations within it to allow you to test lock / unlock. But again this will only allow you in if the N54 is paired to your engine ECU.

KEY CUTTING:

• A locksmith needs your N54 module and will de-solder a chip from it. This data is read and software generates a new key file. (Any of 8x slots) This file dump can be saved down for future key generation.
• The 8 leg chip on a used key fob then requires removal, programming with this information and then soldered back to the key.
• This new key will require synchronising before use.
• Keys are numbered from slots 1 -8 and you can use Star to disable a key if desired, either on temporary basis or permanently.

SYNCHRONISING:

• You cannot pair any old used key to a N54 without the steps above. (Locksmith required)
• The keys use rolling codes. Therefore if your fob has been without power or has been pressed more than 250 times away from the car it will require synchronising. (Several methods best to check your manual)

Crucially, at the time of writing from speaking to my dealer today the N54 for my S500 is NLA from Mercedes. (They checked against my VIN, can see it fine but it's not available to order currently) And if it were available its about 650USD.