Central Locking

SeamusG97

I'm on a roll here today. My van is a Ducato based A-Class. It has central locking to the driver's and side doors both of which are coachbuilt. There's no alarm.
The van has started locking itself at random times. I've tried both taking the key fob out of range and leaving it in the ignition without either making any difference so I'm guessing the fob's not the problem. At one point today it triggered about ten times over the course of a minute and then didn't do anything for the next hour. I had a quick google on the Ducato forums without finding anything relevant so maybe it's not a common thing. I'm guessing it may be either a relay or sensor issue but don't know much about either.
Hopefully there may be more expertise here, especially as the wiring has been inevitably changed from the bog standard during the coachbuilding and this may point to the source of the problem. Sir L. - Your hour has come. .
Thanks in advance for any pointers on what to look at.

autumnalcore

Year/model might help

If it central locks on the mechanical door keys as well as the fob then there will be wires running from the door to the chassis, usually in a rubber bellows/tube. Copper work hardens and so over time in many kinds of vehicles the wires split here and you can get shorts that in older vehicles can cause spontaneous locking / unlocking or opening windows etc. (Also a popular way to break into older car was to slide a fully extended box knife between the door and the chassis to short out the central locking wiring so you sometimes find the bellows and wire insulation cut)

Inspect the condition of the wiring where it flexes, if the visible section looks ok give the loom a good jiggle to see if it triggers the central locking as there may be a short inside the pillar or door. if it looks ok the next thing I would look at is a sticking microswitch / contact in the door locking mechanism.

SeamusG97

autumnalcore wrote: »

Year/model might help

If it central locks on the mechanical door keys as well as the fob then there will be wires running from the door to the chassis, usually in a rubber bellows/tube. Copper work hardens and so over time in many kinds of vehicles the wires split here and you can get shorts that in older vehicles can cause spontaneous locking / unlocking or opening windows etc. (Also a popular way to break into older car was to slide a fully extended box knife between the door and the chassis to short out the central locking wiring so you sometimes find the bellows and wire insulation cut)

Inspect the condition of the wiring where it flexes, if the visible section looks ok give the loom a good jiggle to see if it triggers the central locking as there may be a short inside the pillar or door. if it looks ok the next thing I would look at is a sticking microswitch / contact in the door locking mechanism.

Thanks for the detailed reply. I appreciate it. The van is on a 2009 ducato 2.3jtd chassis. What you're saying makes sense. The side door wiring seems a likely place to look - there was a frayed wire on the sending side i.e. which locked/unlocked the door that I fixed a few years ago. I'll have a look tomorrow or Monday and will post on how I get on.

SeamusG97

Thought I'd cheer everyone up with an update on how I got on with this. Van is still in the garage two weeks later.
Soon after my last posts the electrics went ape**** with lights, indicators, wipers, washers coming on at random times as well as the CL.

It turned out to be the Body Control Unit which is attached to the fusebox under the dash and controls all the electrics in the van. Corrosion on the exposed bits ( due to being left standing over winter ) causes earth issues leading to spurious signals being sent to the various parts of the system. An attempted cure by cleaning the fuse terminals in switch cleaner resulted in the unit dying altogether so a replacement is needed. The van can't be started or moved. The full BCU costs €700 plus VAT from Fiat but my indie mechanic ( Who I trust ) is taking a gamble on ordering the fuseboard part only in the hope that the clever bits aren't the problem. Secondhand isn't an option as it needs to be coded to the ECU and the van isn't moveable to a specialist to do this.
The Joys of Motor(home)ing.
Now off to update my other thread on the broken rooflight.....

SeamusG97

Ok, Back from the edge of your seats everyone. Apparently there's a bloke who may be able to sort it once the indie garage has established that it's not a dodgy earth lead to the engine. I'll be posting the sequel to this cliffhanger sometime next week...