Technical Airbag woes. U1726-87 error

[Steph3071]

Having finally got my connecting cable from Multiecuscan I ran a diagnostic to find out why I have all my airbag lights illuminated.

The diagnostic report says:

Body / BCM (Body Control Module)
Body Computer Delphi (199) MY09
ISO Code: 40 83 51 08 F1
VIN code: ZFA19900000764xxx
Hardware number: 199FL1EU303 - Ver: 03
Software number: 28260602 - Ver: 020B
Errors found:
B10AA-4A - PROXI configuration control - Incorrect component installed
U1726-87 - Airbag Node (NAB) - Missing message
U1705-87 - Receiver Radio (NRR) - Missing message

Dashboard / IPC (Instrument Panel Cluster)
Instrument Panel Marelli MY09
ISO Code: 32 83 CB 08 5D
Hardware number: 50011270001 - Ver: 00
Software number: 04000016022 - Ver: 0122
Errors found:
U1726-87 - No communication with Airbag control unit - Missing message

Dashboard / CTM (Convergence Telematic Module)
Convergence Lauberhorn (Blue&Me)
ISO Code: B5 83 10 89 26
Hardware number: 05035506105 - Ver: 02
Software number: 06.000.C274 - Ver: C274
Errors found:
U1705-87 - Radio Receiver - Missing message

The radio message is to be expected as I replaced the factory unit with a vehicle specific headhunt with CarPlay.

Attempting to read the Airbag ECU MES says "CONNECTION FAILED No response from module...."

I've tested the voltage at the airbag ECU and I have battery voltage at pin 2 of plug A and a good ground at pin 1. I also checked for a short between body ground and pins 7 or 8 which are the CAN lines.
I used an oscilloscope on the CAN lines at the Airbag ECU and can see that CAN Hi and CAN Lo are mirrored output with Hi having a voltage range of 1.5v to 4.9v and Lo having a voltage range of 100mv to 3.4v

I've attached some sample traces in case anyone can see an issue with it.


Unless the CAN signal is incorrect, I think this is pointing to a failed Airbag ECU. What's your opinion on the matter?


Which of the numbers on my ECU are the critical ones to match when sourcing a replacement (image attached) and can MES be used to reprogram a used ECU?

 

[the green vanper]

The problem is know in Ducatos, there are at least 2 companies in the UK that claim to be able to repair most of such cases. One has better reviews than the other.

I've also been told one company in Poland is able to repair the airbag module, however I don't have any experiance with them.

 

[Steph3071]

Having sourced a known good Airbag ÉCU with identical numbers I’m still seeing the same message that MEC is unable to connect to the Airbag ECU and the BCM obviously doesn’t pick it up.

Any suggestions because right now I’m stumped.

 

[the green vanper]

If you are sure you have got the correct cable / adapter to connect with MES to the airbag module, I think the connection between the BCM and the airbag module might be damaged. Don't know if there is a direct connection, but I assume it should be.

However I'm pretty sure that the proxy alignment procedure should be done after a module is swapped. Even with the same one. The serial will be different.

Be sure to backup the actual configuration just in case. Instructions here.

 

[Steph3071]

If you are sure you have got the correct cable / adapter to connect with MES to the airbag module, I think the connection between the BCM and the airbag module might be damaged. Don't know if there is a direct connection, but I assume it should be.

However I'm pretty sure that the proxy alignment procedure should be done after a module is swapped. Even with the same one. The serial will be different.

Be sure to backup the actual configuration just in case. Instructions here.

I purchased my lead direct from multiecuscan and I’m using it with the yellow adapter.

I’ve looked at the wiring diagram and have traced the can cables from pins 7-8 on plug A of the airbag ecu and done a continuity check back to pins 16-20 of plug D on the back of the BCM. Also confirmed battery voltage and earth at pins 1-2 of plug A on the airbag ecu.

Unfortunately I don’t have a backup of the original BCM file. Someone tried to do an alignment using an Autel tool as the mileage was flashing and it removed the missing module completely.
Attempting a pro I alignment now just says the vehicle is properly configured. I would have expected the BCM to pick up the added module, but given that it’s not possible to connect directly to the airbag ecu via MES it doesn’t surprise me that the BCM isn’t picking it up as a new module.

 

[the green vanper]

it’s not possible to connect directly to the airbag ecu via MES it doesn’t surprise me that the BCM isn’t picking it up as a new module.

Isn't it the other way round?

 

[Steph3071]

I purchased my lead direct from multiecuscan and I’m using it with the yellow adapter.

I’ve looked at the wiring diagram and have traced the can cables from pins 7-8 on plug A of the airbag ecu and done a continuity check back to pins 16-20 of plug D on the back of the BCM. Also confirmed battery voltage and earth at pins 1-2 of plug A on the airbag ecu.

Unfortunately I don’t have a backup of the original BCM file. Someone tried to do an alignment using an Autel tool as the mileage was flashing and it removed the missing module completely.
Attempting a pro I alignment now just says the vehicle is properly configured. I would have expected the BCM to pick up the added module, but given that it’s not possible to connect directly to the airbag ecu via MES it doesn’t surprise me that the BCM isn’t picking it up as a new module.

I did a drag test on the pins in plug A of the airbag module. Pin 2 was looser than it should be so I extracted the pin and closed it up slightly.
BCM saw the airbag ecu in MES after doing this, so something to make note of for future reference. Just because back probing a plug shows the correct voltage it doesn’t necessarily mean the module is getting it.

Now the problem I have is that the airbag module I fitted appears to have come from a car with a knee airbag and front seat airbags. These don’t exist on this car so I still have the airbag warning lights.

Is there a way to remove them from the system?

 

[the green vanper]

knee airbag and front seat airbags.

Is there a way to remove them from the system?

I've heard there is. But not with the standard MES options. Some higher level programming I think. The Polish company I've mentionned earlier told me that if the module would not be repairable, he's able to adapt the airbag quantity on the donor module to what is installed on the vehicle.

 

[Steph3071]

I've heard there is. But not with the standard MES options. Some higher level programming I think. The Polish company I've mentionned earlier told me that if the module would not be repairable, he's able to adapt the airbag quantity on the donor module to what is installed on the vehicle.

Once I was able to read the new airbag ecu directly I cleared fault codes on it, switched off and then connected again. This time the faults came up as intermittent. Cleared again. Next time I switched on, no faults. No longer complaining that it can’t find them. Go figure

All put back together and working perfectly

 

[Asteris]

Knee airbag can be turned on/off from the proxi alignment menu of MES.

 

[GettinBetter]

... I did a drag test on the pins in plug A of the airbag module ...

Such a good idea, I need to do that.

But are you convinced it needed a new ECU ?