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Citroen Relay/Ducato padlock help.


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Hi all,


I have a Citroen Relay, 2.2 HDI 2007 that is being converted to a camper, I have posted here after reviewing several threads on the padlock issue and I feel that people here have not only been the most detailed but enthusiastic in solving it, I'll detail what I have here and hope I can get some real answers as opposed to rather unhelpful responses elsewhere.


Mine went in for an MOT and some welding, lock down happened and the whole system shut down when things opened back up, the garage boosted it but it was completely locked out.


The garage then changed the battery and boosted it and it sprung into life but with the immobiliser padlock on.


This then begins the saga to now. I managed to scrape together £200 to have the locksmith find the key code, no change, then said he'd delete the immobiliser. He claims to have done that, I have plugged it back in and the padlock is still on and the van is still no starting. The van will turn over, you can even hear the pump whizzing and there is diesel coming through to the injectors. Auto electrician claims he has done what was asked of him, whatever, I am not going to argue about it, but I am not happy and may as well used the money to start a bonfire in the garden.


I've now checked more into the threads here and noticed people talking about an orange white thin wire. I pulled apart the loom and found it... however, someone has replaced it at some point with three sections. I checked the continuity from pin to pin each end and it's registering on the dial that there is indeed continuity.


I've seen a few other horrible repairs but everything checks as continuity. The padlock comes on within seconds of ignition each time. Sometimes, it flickers on as you first turn the key, then goes out and then comes back on. May just be an anomaly.


I've tried the door opening "reset" (BSI??) thing and nothing happens. Auto electrician said the key is in fact coded though.


So now I am tearing my hair out as it comes ever closer that I could be scrapping a van for a few hundred quid over something silly.


No matter what I unplug ECU and loom wise, the padlock stays on. I can hear clicks in the engine bay but I have no idea what I am looking for solenoid wise if that would be the issue, again I can hear clicking when turning the key before starting.


Two things I see frequent though.


CAL5 - what resistance should I get? I have 1.3 to 1.4 ohms.


Earth strap to the gearbox. It's green and dumpy and doesn't look too clever, but I don't see how that could be the issue.


Before I do call the scrap man. Can anyone add something that I may be missing? I've not found any significant corrosion on any of the plugs to be concerned about and that thin orange white wire was fine. It appears someone has sprayed a dialectic spray to stop corrosion anyway. The main plug into the ECU had a little bit of green but it wasn't on the pins, just the plastic.


All fuses appear to check out. I have no idea what I am doing with the solenoids.


I still owe for the work on the MOT and can't afford to start spending mega bucks on auto electricians nor am I able to buy a new battery or invest in an ECU kit (cheapest was £500) to find it too doesn't work.


Has anyone successfully wired the injectors to fire independent of the ECU through an ignition switch?


Appreciate any head banging and thoughts before I throw in the towel.



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There are 2 thin wires going from the ECU to the coil around the ignition lock

One is grey/white

The coil sends a wireless signal to the chip in the key, and if it doesn't get the right signal back the padlock stays on, and computer says No.

Computer can't stop the engine turning over but it can stop it firing by holding back the fuel.

Its a very low current along these 2 thin wires so all connections need to be perfect.

I would try by passing them with other cable

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Okay I can have another look. You say it holds back fuel, but I have fuel at the injectors if I undo them? It's definitely turning the fuel pump on as I can hear it.


Do you know what current should be through it? I can't find awiring diagram anywhere to even get an idea.

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Greco - 2020-09-20 8:31 AM


Okay I can have another look. You say it holds back fuel, but I have fuel at the injectors if I undo them? It's definitely turning the fuel pump on as I can hear it.


Do you know what current should be through it? I can't find awiring diagram anywhere to even get an idea.


That will be the electric pump you can hear being turned on, which will be pumping the fuel round in circles.

Injection is solenoid operated so the fuel will be there, but the solenoids won't be letting it in to the cylinders until the computer gets a signal back from the key, and says yes.

Wires to the antennae coil around the ignition lock barrel can be joined but if all the connections aren't clean and tight enough it still won't work.

I find the cheeseblock screw down connectors best, and scotchlock connectors the worst.


PS: the connections need to be perfect before you turn the key. If you repair the connections whilst its turned on, you need to turn it off, then turn it on again




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Okay thanks for the input. I will take another look for the grey and white wire and have a look for corrosion. If that doesn't do it then I really am going to have to scrap it.


I've got a new 240 amp rated earth strap to replace on Tuesday but will see if I can pop up before and check the loom again for continuity on that wire.

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OK - good luck and please let us know how you get on.

I have a secret switch in the grey/white wire as an anti theft device.

I have found it stops working after a couple of years as the switch contacts become slightly tarnished

Replace the switch and it works again

Thats how good your connections need to be

If the same switch was on the mains power it was designed for, it would not need replacing because the higher power would push through the tarnished switch contacts.

High end electronics have gold plated contacts to avoid this problem

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  • 4 weeks later...

I've changed the earth strap and been working on it.


Aaaaand I give up. Away she goes for scrap. Thanks anyway, I never found a thing grey and white wire sorry. Well, I did but it wasnt going to the ECU but a relay attached to the inside wing, either way it was wrapped with a brown and white and seemed fine.


Its costing me time and money now so I've thrown in the towel,

I've had silly quotes to come and look at it and it just simply isn't worth it . Think I'll stick to Ford in future!

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