Hi All,

I have just removed an aftermarket UHF radio from my 2003 2.8 JTD Ducato motorhome. I haven't intentionally disturbed/disconnected any factory wiring, but when I tried to start the car, There was no go. I checked there was fuel at the injectors, leaving just injector enabling. Sure enough they're not firing. I purchased a VAG-COM cable and used MultiECUScan to see there is an active U1600 Fault. It is interesting that the Padlock symbol is not illuminated. It doesn't even flash on. I've never noticed if it did in the past.

- Both Keys give the same error code, It happened suddenly, suggesting FOB's are ok.

- Immobiliser Antenna is OK (~40 Ohm)

- I have tried disconnecting the battery several times, from a few seconds to 2 hours.

- Is there a way to see what keys are programmed, I'm wondering if the immobilizer has lost it's memory?

- I have downloaded the eLearn program, but finding the electrical schematics I'm after is a pain. Any ideas what wire signals the ECU the key is ok, I've checked all the fuses and terminals I can find. and the plugs on the Immobilizer module.

I'm 500km from the nearest Dealer, so getting the vehicle to a dealership isn't really an option.

:bang::bang::bang:

James,

I can understand your frustration with the immobiliser.

eLearn takes some getting used to. One poster on here said "That it was like peeling layers off an onion."

Is your vehicle an x230, or an x244 variant? (See first 3 numbers on VIN plate, or registration document.) My information relates to my 2006 x244, but yours could be similar.

I am attaching pdf copies of eLearn circuit diagram E7010 for the code system, and a short description found in eLearn under Descriptions - Engine - Fuel circuit, and scroll down.

Please not that the code receiver drives the dash indication, and that the wire from the code receiver (M020) pin 6, to the ECU (M010) pin 11, is colour coded LG, which translates to light blue/yellow. However as signals are coded, on simple?? test is for continuity. Connector D004 is under the engine bay fusebox, but still inside the plastic housing. Take care to disconnect battery negative while checking, or you could blow a midi fuse. You may not be able to buy one in your location.

Hope that at least part of this may help.

Hi James

Some extra information, and apologies if you have already worked this out.

The immobiliser part of key fobs relies on a fixed coded chip plus tiny coil antenna in the fob. This is interrogated by the vehicle's key code receiver via a circular coil antenna around the key slot. The interrogation also briefly powers up the chip, i.e. it doesn't need a battery (any battery is for the separate remote locking system, if fitted). The chip responds by sending out its code sequence, which is read by the code receiver, and if the code is one that's on its programmed "known list" then all is well.

Because both your keys don't work, it is most unlikely to be a key problem. You have checked the antenna around the key slot. What is most unusual is that the padlock light isn't showing. If there is a problem with a key not being recognised, you would expect the light to come on and stay on.

The +12V power to the key code receiver comes from Fuse F18 via a grey/blue (HL) wire to Pin 3. You should check that power is actually reaching the code receiver on Pin 2.


The warning lamp in the instrument panel E050 is supplied separately with +12V via Fuse F37 and is earthed to illuminate the lamp by the grey/blue wire connected to Pin 2 of the code receiver. You should be able to temporarily remove the wire from Pin 2 and earth it, which ought to illuminate the lamp (ignition must be on) as a basic check that the bulb is OK.

I'm not certain what you mean by UHF radio, is this an entertainment radio or something for 2-way communications ? It's always possible that some connection under the dash has been inadvertently disturbed, or that the original installation was dodgy in some way.

jamesdavies said:

Hi All,

I have just removed an aftermarket UHF radio from my 2003 2.8 JTD Ducato motorhome. I haven't intentionally disturbed/disconnected any factory wiring, but when I tried to start the car, There was no go. I checked there was fuel at the injectors, leaving just injector enabling. Sure enough they're not firing. I purchased a VAG-COM cable and used MultiECUScan to see there is an active U1600 Fault. It is interesting that the Padlock symbol is not illuminated. It doesn't even flash on. I've never noticed if it did in the past.

- Both Keys give the same error code, It happened suddenly, suggesting FOB's are ok.

I'm 500km from the nearest Dealer, so getting the vehicle to a dealership isn't really an option.

:bang::bang::bang:

Click to expand...

Is it possible that the connected UHFset was masking a different issue..

Did you reconnect it ..as a test ?

Are you parked at a normal address: location...?

Couriers do report having issues where some places have radio interference that can mask the key reading..
BUT yours sounds like a fault stopping all immobiliser activity.

Good luck.. do let us know what you find

:idea: any aftermarket security also fitted?

Hi All,

Got back under the bonnet today. I Have some good news.
Thankyou Communicator, for the wiring diagram and notes. and Anthony489 for the further Info. It helped me get to the root cause.

I had checked for 12V supply at the Immobiliser module, but not for earth connection (Brain dead on my part). turns out the Imobiliser was never even powered on. (Black wire pin4 was open circuit). This explained the "No Padlock Light", as its earthed through the Immobiliser to turn on. Pin A02 on D04 (Same earth) was earthed, but no continuity to Pin 4 on immoboliser. Broken wire! While I was at it, also checked Blue/Grey (more of a blue/green) signal wire to ECU. also had no continuity 2x broken wires?

At this point it's worth noting that there are a couple if differences on the Immobiliser plug than on the wiring diagram (as pictured). I believe the Power supply (pin3) is Red/Yellow (Listed as blue/Gray, same as bulb, pin 2), I assume the green is Pin 5 (PC connection), and there is a mystery orange wire on Pin 8, any ideas?



Connected pin 4 on immobiliser to earth, through bulb to save blowing anything up. turned on ignition, Padlock light comes on and stays on (looking good :slayer. Disconnected battery, roughed in new blue/green wire from immobiliser to D04 connector, stopped for lunch. About an hour later, I reconnected battery. No change, no engine start, solid padlock light.

I had a good poke around, now knowing what I was looking for, and found the broken wires (as pictured). it looks like they were sheared at the fire wall as I was pulling the external aerial of the bull bar for the UHF.

So I believe the Immobiliser has lost it's memory and needs to be re-programmed. correct me if I'm wrong. Whats the process to do this? I have the 5 digit CODE code card. I'm hoping I can pack up the Immobiliser and the FOB's and post them off to be reprogrammed, because as mentioned, getting the vehicle to a service centre isnt really an option. I see people using TBD1000 device on Youtube, Its just serial communication, so surely there is a software version of this tool?! Still, buying the tool for ~$350AUD is cheap compared to a 100km tow to the nearest Auto locksmith.

TLR
- I stuffed up and broke the power and signal wire from Immobiliser unit to ECU
- Ran new wires and fixed connections, now have solid Padlock Symbol and still U1600 Error
- How can I reprogram the Immobiliser without moving the car?
- emergency start isn't an option on Diesels.

Thanks again for your help It's been amazing! We're nearly there!

Hi James

I have no direct experience of this, but others have reported that you CAN use the emergency start procedure on a diesel. Maybe the handbook translators were getting mixed up with bump starting ? Anyway, nothing to lose by trying.

Here is the procedure as reported, but having read it I have a feeling there may be some translation issues you will have to cope with.


BOXER EMERGENCY START
This emergency procedure enables you to start the engine only if the engine
doesn’t start because of an immobiliser problem.
If the procedure is interrupted, you must do it again. That’s why it is important
to read and understand properly the procedure before practising it.
This procedure must be done for each starting.
Procedure
1. Read the security code on the card
2. Switch off the ignition. Switch on the ignition
3. Press the accelerator pedal till the diagnostic light switches off (around 8 secs)
4. Release the accelerator pedal
5. Press the accelerator pedal as soon as the number of diagnostic light flashes equals the first number of the security code
6. Press the accelerator pedal till the diagnostic light switches off (around 4 secs)
7. Do stages 6 and 7 for each number of the security code
8. Once you have released the accelerator pedal for the last number, if the light
switches off or flashes for 4 seconds, the procedure is a success and the engine can be started.
If the diagnostic light stays on , the procedure has failed and must be done
again after a delay of 10 minutes. Start the procedure at stage 2. If the procedure succeeds and the engine starts, it means that the problem is an immobiliser one.

The only other thing I can think of is that the "crash sensor" engine safety cutoff switch has been inadvertently knocked during work on the vehicle, and needs manually resetting.

Good Luck

I know this is an older topic but I want to contribute to the U1600 error specifically in combination with no padlock/keycode light on the dash as it may help others save time. I got the U1600 "Key not recognised" error but my solution was different.

The immobiliser unit was defect but it was only the red capacitor which can be changed easily with some soldering. A second hand unit is required (can be bought for €15 or a little more) or finding a compatible capacitor (original is 22Z2, but I don't know which can replace it).

Start of problems
My problems occured after a drained battery and a jumpstart.

Symptoms
I have a Fiat Multipla (facelift version, petrol) and the immobiliser connector looks the same as in the opening post.

• U1600 error in OBD ("Key not recognised")
• Starter motor rotating
• Fuel pump working
• No spark
• No fuel supplied by injectors
• Emergency start code was not accepted: engine light stays on after entering emergency code (it should be blinking when code is accepted)

Possible fixes tried

• Check of fuses and relays in engine bay
• Disconnect battery for a while
• Quick check of cranksensor
• New aerial/antenna for immo (plastic round ring around key barrel).
• Checking earth points
• Checking power to immo unit (both constant and ignition 12V)

Fix that solved my problem
According to the manual the padlock/code sign should always illuminate when checking the key an then turn off or stay on when a problem is detected. The padlock/code sign is not fused seperately in my car. Because of the padlock sign not working I suspected a defect immo unit. I ordered a second hand unit (Magnetti IM100.01, not specific for my car) and connected it. Now the padlock/keycode light worked but got an immobiliser error. This is normal because the second hand immo is not recognised by the ECU.
I measured the capacitors which was a tip from another forum (where I also found the tip of swapping the immo unit) and found out that the red round capacitor gave different resistance results (capacitor size is about 10mm and has code 22Z2).
I desoldered the good capacitor from the second hand unit and swapped it with my broken immo. I'm not good at soldering but this is easy. Car started immediately.



Other fixes likely to solve the same problem

• Flash ECU to "immo off"
  Cons:
  - Immobiliser is deactivated
  - Costs some money (about €175 here)
  
  Pro:
  No more immo problems
  
  
• Clone old immobiliser to working one
  Cons:
  - Very rare service, I only found one website in the US who charge $100 for this (you need to supply both old and new immo).
  
  Pros:
  - No ECU work required
  - Immobiliser still working

I spend a long time finding my solution and was already preparing the car for the scrap yard. I'm happy it now works again and I hope I can help others with these possible solutions.

Hi Agrior,

I have found your post very interesting, and I will bookmark it for future refence. I also very much appreciate that your first post is a gift of knowledge, and not a plea for help.

I cannot relate the photo of your immobiliser to that on my x244 Ducato, but then I have never had to go as far as removing the cover. (I have had one failure to start with padlock symbol, which did nit repeat on second attempt.)

May I correct your identification of the red disc as a capacitor. I realise that it looks similar to a ceramic disc capacitor, but it is in fact a metal oxide varistor, which is a non linear resistor antisurge device. These devices are often connected across the power input of electronic devices to prevent damage caused by electrical spikes in the supply. However buying one matching varistor could be difficult.

I have considered buying a spare ECU flashed to immobiliser off to carry for emergency use. A little expensive, but if measured against a ruined holiday? Fitting a "flashed ECU" may have insurance implications.