Technical Ducato X250 immobiliser light on and won't start

[ducatambo]

hi
resurrecting an old thread since I can't start new ones yet, as a new member.

I have a 2013 Fiat Ducato 130 (model 250)
It has an intermittent immobiliser issue where the Fiat Code (immobiliser) light comes on and it will not start.
It was sitting on a driveway for a couple months and wouldn't start at all until my mate came with a diagnostic computer & cleared a bunch of fault codes. That seemed to fix it.
However now it seems to show the light again and usually after a few attempts at taking the key out & re-trying it starts but I worry about gettting stranded.

connectors, wiring loom & earths checked following advice I've read on this forum. All appears fine. Antenna in ignition barrel was swapped to no effect.

The following error code persists:
Error code: U170587 Radio Reciever Module (RRM) on B-CAN missing message

Following the e-learn diagnostic flowchart indicates the BCM should be replaced.
I spoke to one chap who advertises electronics fixes on e-bay. He said that it's a common fault and that the only way to fix it is to clone it onto a used non-faulty BCM.
Another service, https://bcmrepair.co.uk/ simply said
We can repair the unit if faulty for £280 including VAT. The turnaround time is 24hours.

I'm still scratching my head and now wondering if these repair guys are legit. Any advice would be greatly appreciated

 

[Communicator]

I regret that I am unable to offer a definite fix, or confirm the claims made by possible repairers.

What follows are a few observations on the problem.

I appreciate from my own experience with my x244, that you lose confidence in the vehicle.

There does not seem to be any logical need to withdraw and replace the key, between recognition attempts. My understanding is that switching on the ignition initiates the interrogation of the key by the BCM. See attached eLearn description of the system.

As the failures are intermittant it suggests either a corrupted or reduced signal., including reduced sensitivity of the BCM, which embodies the code receiver function. A corrupted signal could be caused by having a second chipped key on the same ring, while a weak signal could be caused by poor connections, or reduced power output from the BCM which transmits power to the key via the ring aeriel.

Poor connections could be due to oxidised connector contacts, which have a disproportionate effect on the already weak signals involved. Changing the aeriel ring would perhaps improve mtters at that end, but there remains the connections to the BCM.

If the BCM is not interrogating the key correctly, or is suffering from reduced sesitivity when handling the response from the key, then changing the BCM seems a sensible if expensive course of action. However a technician with more specialist knowledge of the BCM and who is aware of the cause of the problem, may only have to change a single tiny component on the BCM, which is a complex computer module.

 

[ducatambo]

Thanks for your communication. I had done quite a bit of research on this forum before without posting anything.
Losing confidence in the vehicle is definitely an issue as this is a camper build and I will be traveling abroad.
Like I said, connectors and wiring have been quite extensively cleaned & checked leaving the BCM as the only unexamined link in the chain.
I saw a post on this forum where someone claimed to have resolved the immo problem by soldering a couple of components onto the relevant part of the BCM, to stabilize the power supply to it.
Best quote I've had so far for repair is from autotronics: £180+VAT to repair or £48 to check & test if they don't find anything. That's a bit more like it. It was hard to repair those bcmrapair guys are not scammers. Their response seemed to be like "We can fix it, send us your money"

 

[ducatambo]

If the BCM is not interrogating the key correctly, or is suffering from reduced sesitivity when handling the response from the key, then changing the BCM seems a sensible if expensive course of action. However a technician with more specialist knowledge of the BCM and who is aware of the cause of the problem, may only have to change a single tiny component on the BCM, which is a complex computer module.

well, I sent the unit in to autotronics. After being told they could test/fix it before I sent it in, I am now told they can't do either. The only thing they can do is a data transfer (clone) on to a replacement unit. They say to check it on my vehicle to see if it works. Of course, since a new unit will hold a different security code, there's no way to test if that side of it (immobiliser/code circuit) is actually in working order. So now I'm a bit dubious what to do

 

[the green vanper]

Depending on the error type I find it quite normal that a part of them cannot be repaired

 

[ducatambo]

i saw a post on another forum where someone was talking about making some physical repairs to the BCM to solve exactly this problem:

I replaced the SMD cap between the TX pin of the RFID transceiver chip and the antenna, the transceiver IC and the 3x electrolytic capacitors. I also placed a zener diode and a 100nf capacitor across the power supply to the transceiver to clamp any transient spikes on the power supply to it.

however this is for an older model (2008 ducato... although still marelli BCM). tinkering with the electronics on the BCM is beyond my expertise.
The post at least confirms that this can be a BCM issue.

I am a little confused by autotronics' behavior since I've seen posts on this forum where people discuss sending items in to them to be tested. I got autotronics to return the item.
There is another company which can clone the BCM onto one which they supply themselves, for around £250. This seems like the best option.

 

[ducatambo]

update:

I bought a secondhand BCM. however the problem seemed to go away (the van was starting, not immobilised) so I didn't go ahead with the clone and sent the BCM back. I also bought a toughbook and licenced MultiECUscan.
Immobiser problem comes back :-(

Running diagnostics with the immo/code light on, MultiECUscan is picking up the BCM (with faults) but can't connect to the ECU. ECU is showing up on CANbus info as configured but not active.

So.. I bought a full set of donor code-matched ECU, BCM, key, barrel and fusebox. According to E-learn the code system is not in the barrel, rather the BCM so rather than swap the barrel I swapped the transponder board from the donor key. I swapped out the instrument cluster, BCM and ECU.

Prior to doing this I opened up underneath the fusebox, checked the wiring. Although there had been water ingress under the bonnet there were no signs of shorts or fraying damage to the cables where they come into the fusebox. I'd previously opened and checked the loom up to where it goes into the fusebox.. There was a bit of corrosion on the earthing point on the bracket the ECU mounts onto. I figure this is an anti-static measure rather than a main earth but I'm not sure. Anyway I cleaned it along with all the other connectors, none of which looked corroded.

There is a point on the wiring to the instrument panel where some wires have been spliced in and then removed. There's a redundant earth strap under the instrument panel too but it looks as if it went to whatever has been removed rather than into the loom. It didn't appear damaged and I taped it up.

Upon turning the key, instrument panel lights up, no immo/code fault light, others instead, engine turns over but doesn't fire up, I get the diagnostics on there. See attacked photo: BCM isn't coming to life. I double-checked the connectors, still no joy.

I note that 'Radio Receiver Module' doesn't refer to the antenna that picks up the key code, rather it refers to audio/navigation unit which had been removed.

I swap everything back. Code light is back on. Diagnostics are picking up the BCM this time, again not connecting to ECU with a consistent fault code on the BCM to confirm this. BCM and Airbag module not communicating with each other either.
If the BCM can't communicate with the ECU to resolve the immo code it makes sense that the vehicle is immobilised.

Right.. OK, the module swap didn't fix the problem. I figure the donor BCM is a dud but I wonder if I could be missing something.

So what now? I figure the fault could be (still as originally speculated) the BCM, ECU, power supply to ECU or on the CAN line. I've opened up & checked the looms under the bonnet but not on the dashboard. I don't know if there would be any sense in checking the ones under the dashboard. What my mechanic friend started doing but ran out of time, was testing resistance/continuity on the CAN lines (a bit of research time on e-learn is required for this). Maybe that's my next task, i dunno. Either that or get an auto electrician involved. Thoughts?

 

[Googlebot]

Do you not need to proxi align all the new components?

It won’t recognise them if you don’t I believe.

 

[Code Breaker]

Just a thought, could you get immobiliser deactivated and fit an aftermarket alarm immobiliser, that way it'll get you going?

 

[NZGrahamO]

Hi

I had the same problem with my 2016 Ducato with immobilizer not allowing the motor to start.
After checking just about everything using Multi ECU scan tool I found that the C Can signals between engine management control unit ( M010 ) and the body computer ( M001) at times was not working hence bringing up the immobilizer light and no engine start.
The problem was plug A on M010 pins 48 and 49 were not making contact at times bringing up the immobilizer light and no engine start.
I dismantled plug A and fitted new pins. Problem fixed.
Also check plug B pins 83 and 84 on ( M001 )
Also check wiring between both ECUs
M001 Plug A pins 48 / 49 connects to M010 plug B pins 83 / 84

Graham O