Disable faulty alarm system

[BRABUS124]

Hi i got a troible some W124 CE 320 1996

It has the infrared keys and centrallocking system currently also not working. Sometimes it does, fuses checked replaced no difrence. But the car will also not start now. The car worked before with just no infrared key and also mechanical key not activaring the central locking system. But the car started and could be driven.

But now sudently it won't start either.
The starter cranks all day long. But it wont start even 1 pop nothing. And I don't hear the fuel pump prime either,

It has new wireharness for 2 years working fine also from Kurth clasic.

So heres what's been tried.

First tried start spray also no effect. Means ignition is also missing.

So measures the crank sensor that are the type with plug on the sensor and not wire attached. It measures 0.68 K ohm. Off the car a new bought febi was measured to 1.1 Kohm so der tly a big difference. But no effect.

Another Engine ECU tried with green fuel pump relay as well from another working car with also the OVP relay. Still no effect.
Battery is fully charged new.

So I tried unpluging the Alarm unit under the passager seat foot well. No effect and there's no silver relay behind the dash instrument Either.
But the alarm unit in this car has not 2 plugs but 1 big see picture and has a 140 number as if it's from 140 model latest type.
It still won't start but cranks fine. Coils plugs seams ok. Why would all 6 sudently fail. Right.

So I at a dead end here. What the next thing here?
I mean no fuel pump priming and no ignition. It must be related to the alarmsystem,

 

[gsxr]

Since your car is a 1996... does it have the immobilizer? What is the part number of the HFM computer?

 

[BRABUS124]

Since your car is a 1996... does it have the immobilizer? What is the part number of the HFM computer?

To be hornet the car, was born with a 300-24 in 91 but the car, went to Germany and got fully drive line and everything from another coupe 320 all very highly professional swaped into it and the car worked for years.

But it has this immobilazer box showed in the picture. Becker module. But ive never seen that type i a 124. With a 140 part number. It has the black botton in console with a red diode in. So I guess it's been moved compnte, system centrallocking vacum pump with IR system and sensors and that immobilelizer and all to fit for the rest of the system

The HFM boks number ill have to check to morrow but it has worked for years so the parts should be ok..?

 

[gsxr]

That's an alarm system module for a 140 and 463, but it's not an immobilizer. The DAS / immobilization function was part of the ECU on some models starting around 1996, which is why I asked. This will usually let the engine crank but not fire.

The alarm system usually has a rudimentary theft protection that prevents the starter from engaging, but your starter is working normally.

 

[BRABUS124]

That's an alarm system module for a 140 and 463, but it's not an immobilizer. The DAS / immobilization function was part of the ECU on some models starting around 1996, which is why I asked. This will usually let the engine crank but not fire.

The alarm system usually has a rudimentary theft protection that prevents the starter from engaging, but your starter is working normally.

View attachment 237324

Ok. So this unit never belonged to a 124?
So the donor car they made the transfer from could be a S320 W140 and they just moved the IR systemet to this car as well?
Its strange thing because it has worked with the Ir and central locking system but sudently it became dead the Ir and central locking system no reaktion from ir sensors light or vacum pump. All dead. But car would still run. But now it won't
Im not sure the donor car is from 1996 but the crank sensor on engine is the plug type not the usually sensor with wire on.
Wireharness is fit right and has 124 number.
So sensor type with plug on must also be in 124s later models. Because Ealy 320 does not have crank sensor with plug but the crank sensor with wire on.

 

[JC220]

You need to get the car onto MB DAS computer and read the codes and drive authorisation status.

It does sound to me like an immobiliser issue. DAS would show if that is the case if the start authoisation is off. Then I think you will require the services of an automotive locksmith who is familar with this vintage of car.

My advice is fix it correctly this way and never with an aftermarket immob bypass box. Those can fail and leave you stranded.

Also check your IR key is sending signals with a phone camera. Replace the fob batteries. Try a spare key and see if anything changes.

I have fixed several cars like this, it can be done.

 

[BRABUS124]

You need to get the car onto MB DAS computer and read the codes and drive authorisation status.

It does sound to me like an immobiliser issue. DAS would show if that is the case if the start authoisation is off. Then I think you will require the services of an automotive locksmith who is familar with this vintage of car.

My advice is fix it correctly this way and never with an aftermarket immob bypass box. Those can fail and leave you stranded.

Also check your IR key is sending signals with a phone camera. Replace the fob batteries. Try a spare key and see if anything changes.

I have fixed several cars like this, it can be done.

Its not that technic at all,
This is older type of alarm system
Of cause the fob key has new batteries and is testet good on another car but it dossent help anything as lige kg as both systems are dead as in totally dead. Nothing reaktion on anything regarding sensors res og green light nor will the central lockimg work from manually activating the door pins or inside car push botton for lock and u lucking the car. Meaning i think this is a ground or circuit missing power. It did came to life one day everything worked again out of the blue air. Strange. All locks working etc. But now it also affects the alarm system the red diode in the console also not lit up flashing!
So no power og ground to the module letting me into just want to get rid of it. Bypass it.
But how. Car has been working with another ECU before as well so this is not some cumputer related system it's to old for that.
It has analog codes witch had a code for sorted driver doors sensor and it lit up red all the time no matter the lovk stage. . But that was replaced and has momentarely worked after that as a connection sudently was created. So I want this system out of the car. But how?

 

[JC220]

Its not that technic at all,
This is older type of alarm system

You'll be surprised. My locksmith said my 90's merc alarm immolisers were advanced coding he was not ecpecting. Similar architecture to modern systems. It is MB so perhaps not that surprising.

You need it on DAS as I said.

 

[BRABUS124]

You'll be surprised. My locksmith said my 90's merc alarm immolisers were advanced coding he was not ecpecting. Similar architecture to modern systems. It is MB so perhaps not that surprising.

You need it on DAS as I said.

I do repairs on electrical components on V12 M120 etc. Digital Mixed with analog so yes I know the very well. With use of canbus from 1988 between units.

But this 124 eksist also without this alarm unit. And without IR system on that same engine module HFI etc. So it's possible to remove it for sure withiut the need of ANY DAS as a proff the car ran perfectly with anotjer 320 unit from a difrent car 124 so it's not that i not open to new stuff, but if it were that aevanced it wouldn't have worked with that other ECU from another car.

The problem here is just simply Its failing with the power for the module. So I want to strips it out the car. Without having to dig all wires etc out. There's a way of doing it without any program. It's just about what to disconnectez and where to short the right curcuit. To make it run as if the optional alarm unit was never fitted in the car.
The ECU from this car was also tried in another 124 320 working just fine without having ir key system but the redular boring vacum central locking to it.
I might be the one figuring it out. That's ok. Ive done investergating work with diagram wires before,

 

[Surf Blau]

I do repairs on electrical components on V12 M120 etc. Digital Mixed with analog so yes I know the very well. With use of canbus from 1988 between units.

But this 124 eksist also without this alarm unit. And without IR system on that same engine module HFI etc. So it's possible to remove it for sure withiut the need of ANY DAS as a proff the car ran perfectly with anotjer 320 unit from a difrent car 124 so it's not that i not open to new stuff, but if it were that aevanced it wouldn't have worked with that other ECU from another car.

The problem here is just simply Its failing with the power for the module. So I want to strips it out the car. Without having to dig all wires etc out. There's a way of doing it without any program. It's just about what to disconnectez and where to short the right curcuit. To make it run as if the optional alarm unit was never fitted in the car.
The ECU from this car was also tried in another 124 320 working just fine without having ir key system but the redular boring vacum central locking to it.
I might be the one figuring it out. That's ok. Ive done investergating work with diagram wires before,

I retrofitted an original alarm system in my W201, and on that model it is completely separate from the rest of the car like you say yourself as well - the only thing it does on the older cars is to monitor the door, hood and boot switches once it has been activated. From my - admittedly not 100% clear after so many years - memory the alarm unit looks the same as the white Becker unit you refer to in your post.

It's my understanding that this is the basic system in a 124 as well, but for the later models it was possible to specify an immobilizer as has been pointed out above, so perhaps the donor car for yours had that? I don't suppose you have any info at all about the donor car? If there is an immobilizer it must be located around the ignition lock for it to read the "code" from your key, so you could have a look around there and see if you find any signs of one perhaps.

 

[Surf Blau]

I had a quick look at an online EPC-solution to see if I could figure it out, but the only concrete information I found was that the wire harness for the alarm was different with and without immobiliser:



This online EPC is not detailed enough (for me) to figure out which other parts are related to the immobiliser unfortunately. Perhaps someone here with a full version are able to figure out any more?

 

[gsxr]

I'd still like to know the part number of the HFM ECU. If it's the immobiliser type ECU, it needs some sort of signal to authorize starting the engine.

However if it's NOT an ECU with immobiliser function, it should not matter what alarm system is present - the engine should fire if the starter engages.

 

[JC220]

I'd still like to know the part number of the HFM ECU. If it's the immobiliser type ECU, it needs some sort of signal to authorize starting the engine.

However if it's NOT an ECU with immobiliser function, it should not matter what alarm system is present - the engine should fire if the starter engages.

If it had start immob function DAS would show it too. Easy way to check.

 

[Surf Blau]

If it had start immob function DAS would show it too. Easy way to check.

Do you mean the diagnostic software by DAS?

 

[JC220]

Do you mean the diagnostic software by DAS?

Yes which is essentially the only MB software that reads this era of MB.

OP hasnt provided much except alot of symtoms. It needs alot more investigation and Id start with DAS as first logical step.

 

[Surf Blau]

Yes which is essentially the only MB software that reads this era of MB.

OP hasnt provided much except alot of symtoms. It needs alot more investigation and Id start with DAS as first logical step.

I have HHTWIN (which DAS emulates when connected to a 124 or similar aged cars) myself which I use on my own car, but I had no idea it could pass on such information.

 

[JC220]

I would also be testing the crank sensor more to ensure it is generating a signal to rule out sensor or pickup issues.

 

[BRABUS124]

I retrofitted an original alarm system in my W201, and on that model it is completely separate from the rest of the car like you say yourself as well - the only thing it does on the older cars is to monitor the door, hood and boot switches once it has been activated. From my - admittedly not 100% clear after so many years - memory the alarm unit looks the same as the white Becker unit you refer to in your post.

It's my understanding that this is the basic system in a 124 as well, but for the later models it was possible to specify an immobilizer as has been pointed out above, so perhaps the donor car for yours had that? I don't suppose you have any info at all about the donor car? If there is an immobilizer it must be located around the ignition lock for it to read the "code" from your key, so you could have a look around there and see if you find any signs of one perhaps.

Eksactly my point. This systems are normally stabdalone systems but that said. This is a newer type than the once normally found in 210/124/126
So I know these older types.
You just pull the 2 plugs out of the becker alarm unit. Up til 1993 Job done. Very unprofesional made in my opinion.
From 1993 they also fitted a silver relay behind the dash that need a short between 2 of the pins to have iginition working. That's also really easy job but a bit more profesional done.
But from 1996 around that year they made even futher stuff like this unit that obviusly are not standart or use in a 124 so my thought is this complete engine swap came from a W140/R129 320 M104 engine and they fitted this alarm/imobilizer system into it as well.
But it dossent make sense it's using the 124 ir sensors at the doors and have the 124 centrallocking vacum pump. So it might be that this system was made for the 124 even though the alarm/imobilizer unit is not mentioned i EPC for use i a 124

But as I could use the cars Engine ECU in anotjer car never born with alarm/imobilazer this ECU must not need any signal from an alarm/imobilizer unit to run. That's the logic Im using. And even more proffable is it that another ECU from anotjer car with no alarm imobilizer systems works in this car as well.
Confirming the logic even more.
So if this cars engine ECU would have some sort of need for an aproval signal to start. It dossent make any sense it works in another car without any alarm/imobilizer right?
Futher if another ECU without any of this does work in the car "before the fault happened" this would not be possible either.
And it's tried also after this error occoured and won't work. Buikding the logic even more that if a non alarm/imobilizer engine ECU now also dossent work in thus car. It means this 140 partnumber alarm unit is in deed a stabdalone system that cuts the fuel and ignition outside the engine ECU meaning no software interfeerence but pure hardware by wire interferens out side of the engine ECU. That logic fits perfect. But it must work together this ir / central locking system to be able to be activated at least. And that system has not been working at all lately.

So Im Keen to find out to bypass the module as it is a stabdalone system not talking to the engine module.

So I might need plugs pinout for this 140 partnumber alarm/imobilizer unit to figur out what's what and where to look for errors or how to find a way to bypass it.

 

[BRABUS124]

I would also be testing the crank sensor more to ensure it is generating a signal to rule out sensor or pickup issues.

Crank sensor was change alreaddy and old measures 0.67 K ohm new one 1.1 K ohm.
But despite that. Still won't start and another ckue is as well. No fuel pump signal/power as well. So must be an imobilizer thing. But I would try measure it anyway yes

 

[JC220]

Crank sensor was change alreaddy and old measures 0.67 K ohm new one 1.1 K ohm.
But despite that. Still won't start and another ckue is as well. No fuel pump signal/power as well. So must be an imobilizer thing. But I would try measure it anyway yes

Have you looked up the WIS ohm spec? Need to do that and compare.

Also a Febi crank sensor would be made in china more than likely! Would not be my first choice.

 

[gsxr]

I have HHTWIN (which DAS emulates when connected to a 124 or similar aged cars) myself which I use on my own car, but I had no idea it could pass on such information.

Correct. The 1990's cars require HHT-Win, which is launched by DAS.

 

[gsxr]

Have you looked up the WIS ohm spec? Need to do that and compare.

Also a Febi crank sensor would be made in china more than likely! Would not be my first choice.

I missed that the crank sensor was Febi, which I agree is not optimal. However if there was no change with old or new sensor, that may not be the issue.

 

[JC220]

Correct. The 1990's cars require HHT-Win, which is launched by DAS.

Oops yes its HHT-Win which I use from DAS.

I missed that the crank sensor was Febi, which I agree is not optimal. However if there was no change with old or new sensor, that may not be the issue.

Ideally watch the crank speed data in HHT-Win to see if the ECU is receiving the speed signal.

@BRABUS124 Do you have an MB diagnostic laptop and Mux? If you work at other MBs including V12's I'm assuming you do have one.