Technical Immobilizer Immobiliser or how my 2003 2.0 swb fiat Ducato left me stranded.

[StHawk]

Soooo here is the update.
I got my Ecu back and plugged it in and it works!!
The only issue I have is the immobilizer light is still on.

However, now my headlights aren’t working and I can’t figure out why.
I checked the fuses in the engine compartment and they are all good..
I thought maybe I left a ground loose after chasing all the ground wires down but the ground on the back of the headlight plug is connected through continuity to the ground on the battery.
I’m stumped at the moment.

Any suggestions would be helpful.

Thanks,
Jeremy

 

[Anthony489]

Hi Jeremy

This is my understanding of how the immobiliser works for your age of van. When you twist the key to turn on the "ignition", the immobiliser unit in the van sends out a burst signal at a low radio frequency (about 125 kHz) via the coil round the lock barrel. This is picked up by the nearby tiny coil in the key fob, and sent to the immobiliser chip in the key. The pulse signal provides enough energy to briefly power up the chip (it has no battery supply) and the chip then sends back a burst of coded signal. The code is determined when the chip is programmed, and normally cannot be altered. (more modern systems have rolling codes, but that's another story).

So the only parts in the key fob are the tiny coil and the chip. These are small and rugged, and it's hard to see how these could fail or become corrupted unless the keys are dropped. To test the key, it would need to be placed close to a tester simulating the vehicle immobiliser.

Back at the vehicle unit, the received code is compared in the immobiliser with its "good code list", which will correspond to the code(s) of the key(s) for the vehicle. It's possible that this list has become corrupted, but it should be possible to re-write it. This may be a Fiat job.

The remote locking system in the key relies on a battery and usually operates at 433 MHz. It is completely separate and has no connection with the immobiliser.

 

[StHawk]

Anthony, yes that’s what I gathered. And after speaking with the Ecu guy he showed me how it works… the problem was there was no code in the immobilizer anymore essentially it had been scrambled.
Now it doesn’t exist. So the van drives again.

Now the problem has become my dip beams and I have no idea what happened there…

 

[Anthony489]

Hi

Here is a schematic for the headlights. It is for the X230 model, but I cannot guarantee that it applies to your van - Fiat liked to change things !

The dipped headlights are supplied via the contacts in Relay 2605, then individual fuses F7 and F8. The coil of Relay 2605 is earthed at one end, and gets a 12 volt feed at the other end from the Light switch 2600 via the Dip switch 2001. When you go to main beam, this live feed is diverted by the dip switch to Relay 2606 instead, to turn on the Main beams.

If you have lost both Dip beams but everything else is OK, I suggest you check Relay 2605 is getting 12V to its coil, and has ground on the other end. It should click when dip beam is turned on. If Relays 2605 and 2606 are the same type try swapping them over.

 

[Mike1alike]

Anthony, yes that’s what I gathered. And after speaking with the Ecu guy he showed me how it works… the problem was there was no code in the immobilizer anymore essentially it had been scrambled.
Now it doesn’t exist. So the van drives again.

Now the problem has become my dip beams and I have no idea what happened there…

So the technical fix for IMMO problem was to deactivate the IMMO from ECU?

 

[jackwhoo]

So the technical fix for IMMO problem was to deactivate the IMMO from ECU?

Hi Mike,

That is a solution to get the original poster moving again on this occasion.

Regarding headlights the shrouds around the steering column have been removed recently and the vehicle has had new bulbs fitted recently. This may sound a bit crazy but check both bulbs work by applying battery voltage- possible bad bulbs. Check connections under steering column covers.

If fast fix required to get from Holland to italy run a new (fused) wire via a switch direct to dip beam bulb connectors.

To OP thanks very much for updates-I am cheering for you to win.

Best wishes to all
Jack

 

[StHawk]

So. An update. I apologize for not getting back sooner. We made it back to Italy. The van works fine. The headlight issue is a bad connection in the fuse block… I’ll deal with it later.
Sooo
The solution was indeed to have the immobilizer circuit…removed from the Ecu.
The ONLY other option was to find a key/immobilizer/ Ecu set from a working van.or buy new.
It seems that the next model or upgrade there were options but not in the early 2000 series.
The fix cost me €150. Totally worth it.
Thanks for everyone’s help. I now know more about this Ducato than I ever wanted to know. Lol

Jeremy

 

[NigelNovice]

Ok. Current situation, pardon the pun…
I repaired all the grounding points, cleaned, sanded, retapped the hole for the ground strap.
I bought a proper cable end for the ground lead to the battery and put everything back together.
Still no joy. Had ANWB, (AA, or AAA in UK or USA) and this time the guy was more helpful and communicative. He says the key isn’t sending a signal. We tried to get the key apart, but neither of us could without destroying it. So if there is a trick that would be nice to know and if someone has done it tell me or point to a video but since there is nothing in this key except the chip it’s sealed up tight…
So here is what I think happened.
The rust to the ground strap was so bad that it was causing issues. I could pull the cable off the battery and it would fix the issue.
I pulled the cable off the battery with the key in the ignition, and this caused the immobilizer to scramble and come on.
Nothing turns it off in the first series of immobilizer. Once that light appears on the dash. You are done.
The only repair is to have someone recode the key, to communicate with the immobilizer unit.
So. I pulled the ECU, the immobilizer unit and took them and the key to a guy who repairs Ecus.
I will let you know the outcome. Thanks for staying with me.
If I am misunderstanding how this works chime in.
Thanks again,
Jeremy

Hi StHawk,
I have a similar problem, going to send bits off for checking, trouble I can't find the immobiliser unit - the smaller one in your photo, several places suggested - behind cab fuse box, behind steering column but I cant see it - where was yours please? - Nigel

 

[Communicator]

Hi Nigel,

Welcome to the forum. What we like to see in return for our efforts, is a post detailing the eventual fix.

Unfortunately you have not confirmed the model, or even the manufacturing year of your vehicle. In order to stop me or others wasting our time, please post your model as soon as possible. The model number is the first three numbers in the VIN, which for an x244, would have the form ZFA244xxxxxxx.
To avoid going outside in this miserable weather, I suggest looking up the VIN in the V5C registration document.

 

[NigelNovice]

Hi Nigel,

Welcome to the forum. What we like to see in return for our efforts, is a post detailing the eventual fix.

Unfortunately you have not confirmed the model, or even the manufacturing year of your vehicle. In order to stop me or others wasting our time, please post your model as soon as possible. The model number is the first three numbers in the VIN, which for an x244, would have the form ZFA244xxxxxxx.
To avoid going outside in this miserable weather, I suggest looking up the VIN in the V5C registration document.

Now filled in, cheers

 

[Communicator]

Now filled in, cheers

?????????

 

[NigelNovice]

?????????

My profile and garage

 

[jackwhoo]

My profile and garage

Great but please put it in any questions you ask , it makes it much easy to help, and anyone reading later will be able to follow.

 

[Communicator]

Now that the model, x250, has be resolved, may I point out that this thread relates to the earlier x244 mocel, which was manufactured from 2002 to 2006.

On the x250, there is no discrete code receiver module. The function is performed by the Body Control Module (BCM). The signals from the antenna ring around the ignition switch, will be at a low voltage. On my x244 I reseated the antanna connector at the code receiver, applying contact cleaner. This has cured the code failures that I had previously been experiencing.

On the x250 the antenna connects directly to the BCM. Page 126 of the x250 Training Manual,( which is available in the downloads section, see top of page), shows "immobiliser antenna" connections at pins 7&8 of a 52 way connector at lower RH corner of BCM, as viewed in cab.